Modular rimfire handgun

Abstract

A firearm comprising a receiver, a barrel removably coupled to the receiver, a bolt assembly housed within the receiver, and a set screw configured to bias the barrel against the receiver to secure the barrel in a fixed position relative to the receiver. The barrel and the receiver utilize a locking system comprising an axial lug and a rotational key for repeatable barrel positioning. The axial lug may be positioned on the barrel and configured to engage with an axial pocket defined in the receiver to constrain axial movement of the barrel relative to the receiver. The rotational key may be positioned on the barrel and configured to engage with a rotational pocket defined in the receiver to constrain rotational movement of the barrel about a longitudinal axis of the barrel. The receiver may define an elliptical opening configured to receive the barrel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 746,497, titled RIMFIRE HANDGUN, filed January 17, 2025, the entirety of which is hereby incorporated by reference herein.TECHNICAL FIELD

[0002] The present disclosure relates to firearms, and more particularly to a semi-automatic rimfire handgun with a modular barrel system, an optional delayed blowback bolt assembly, and an optional magazine configured to accommodate magnum rimfire cartridges.BACKGROUND

[0003] Semi-automatic rimfire handguns have gained popularity among recreational shooters, competitive marksmen, and firearms enthusiasts due to their compact designs, manageable recoil characteristics, and relatively inexpensive ammunition. These firearms typically employ internal bolt mechanisms that cycle within a receiver to chamber, fire, and eject rimfire cartridges. Various approaches have been developed for coupling barrels to receivers, with some designs utilizing press-fit arrangements that provide rigid connections but limit user serviceability, while other designs employ set screws or similar fasteners that permit barrel removal but may not consistently maintain barrel alignment after reassembly. Existing rimfire handgun platforms designed for standard .22 LR cartridges often utilize straight blowback operating systems, which rely on bolt mass and spring tension to control the firing cycle. However, higher-pressure magnum rimfire cartridges such as .22 WMR and .17 HMR present challenges for straight blowback systems due to the increased chamber pressures and the need for positive case retention during firing. Magazine designs for rimfire firearms must accommodate the rimmed nature of rimfire cartridges, which can lead to feeding issues such as rim-lock when cartridge rims overlap improperly within the magazine body.SUMMARY

[0004] In some examples, the disclosure describes a firearm that includes a receiver, a barrel removably coupled to the receiver, a bolt assembly housed within the receiver, and a set screw configured to bias the barrel against the receiver to secure the barrel in a fixed position relative to the receiver. The barrel and the receiver utilize a locking system that includes an axial lug and a rotational key for repeatable barrel positioning.

[0005] In some examples, the disclosure describes a firearm that includes a receiver, a grip extending from the receiver, a barrel coupled to the receiver, a bolt assembly housed within the receiver, and a charging handle coupled to the bolt assembly and connected to a carrier via a charge handle link. The bolt assembly includes a locking block and the carrier. The locking block is configured to engage a locking surface of the receiver when the bolt assembly is in a locked position. An angled interface between the locking block and the carrier is configured to cause the locking block to disengage from the locking surface when the carrier moves rearward. Rearward movement of the charging handle causes the carrier to move rearward and disengage the locking block from the locking surface.

[0006] In some examples, the disclosure describes a magazine for a firearm that includes an injection molded magazine body configured to retain rimfire cartridges in an angled orientation, a stamped backer plate attached to the injection molded magazine body, and a follower positioned within the injection molded magazine body. The injection molded magazine body includes a plurality of raised posts and the stamped backer plate includes a plurality of holes configured to interface with the plurality of raised posts to secure the stamped backer plate to the injection molded magazine body. The follower is configured to pivot to support the angled rimfire cartridges.

[0007] The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure and are not restrictive.BRIEF DESCRIPTION OF FIGURES

[0008] The disclosure can be understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings.

[0009] FIGS. 1A and 1B are a conceptual diagram illustrating views of an example firearm.

[0010] FIGS. 2 and 3 are conceptual diagrams illustrating a rearward perspective view of the firearm of FIG. 1 showing an extended charging handle.

[0011] FIG. 4 is a conceptual diagram illustrating a cutaway view of the firearm of FIG. 1 exposing internal components.

[0012] FIG. 5 is a conceptual diagram illustrating a cutaway view of the firearm of FIG. 1 showing a hammer in an uncocked position.

[0013] FIG. 6 is a conceptual diagram illustrating a rearward perspective view of the firearm of FIG. 1 showing an exposed recoil post.

[0014] FIG. 7 is a conceptual diagram illustrating a cutaway view of the firearm of FIG. 1 showing a trigger mechanism and a trigger return spring.

[0015] FIG. 8 is a conceptual diagram illustrating a perspective view of a bolt assembly of the firearm of FIG. 1.

[0016] FIG. 9 is a conceptual diagram illustrating a cutaway perspective view of a magnum bolt assembly.

[0017] FIG. 10 is a conceptual diagram illustrating an exploded perspective view of the magnum bolt assembly of FIG. 9.

[0018] FIG. 11 is a conceptual diagram illustrating a perspective view of the magnum bolt assembly of FIG. 9 showing internal components.

[0019] FIG. 12 is a conceptual diagram illustrating a cross-sectional view of a portion of the magnum bolt assembly of FIG. 9.

[0020] FIGS. 13A and 13B are conceptual diagrams illustrating side cross-sectional views of the magnum bolt assembly of FIG. 9 showing a locking block in locked and unlocked positions.

[0021] FIGS. 14A and 14B are conceptual diagrams illustrating isolated views of a locking block and a carrier in locked and unlocked positions.

[0022] FIGS. 15A through 15C are a conceptual diagram illustrating various views of a magazine configured to retain magnum rimfire cartridges.DETAILED DESCRIPTION

[0023] For purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the disclosure is intended by the illustration and description of certain embodiments of the disclosure. In addition, any alterations and / or modifications of the illustrated and / or described embodiment(s) are contemplated as being within the scope of the present disclosure. Further, any other applications of the principles of the disclosure, as illustrated and / or described herein, as would normally occur to one skilled in the art to which the disclosure pertains, are contemplated as being within the scope of the present disclosure.

[0024] Referring to FIG. 1, a firearm 100 may include a receiver 102 that forms a main body of the firearm 100. The receiver 102 may be constructed from case hardened steel, providing durability and strength to the firearm 100. A grip 104 may extend downward from the receiver 102, providing a holding surface for a user. The grip 104 may be constructed from a high-strength polymer, such as a polyamide, for example, Grivory GV available from EMS-CHEMIE, Sumter, South Carolina, which offers a balance of durability and weight reduction. The grip 104 may be designed with a Savage Arms 1911 style angle, providing a familiar and ergonomic feel for users. In some cases, the grip 104 may be designed to be compatible with 1911 grip panels, allowing for customization of the grip surface. The firearm 100 may include an integrated accessory rail 105 for attaching accessories such as lights or lasers.

[0025] A trigger 106 may be positioned within a trigger guard 108, which is located below the receiver 102. A barrel 110 may be coupled to the receiver 102 and may extend forward from the receiver 102. The barrel 110 may be constructed from 4140 steel. A forward sight 112 may be mounted near a front end of the barrel 110, while a rearward sight 114 may be positioned on a rear portion of the receiver 102 to facilitate aiming. The rearward sight 114 may be mounted using a dovetail system, which may allow for adjustment or replacement of the rearward sight 114 to suit user preferences.

[0026] As further shown in FIG. 1, a recoil post 116 may be positioned at a rear of the receiver 102. A bolt assembly 118 may be housed within the receiver 102. The bolt assembly 118 may be fabricated from 4140 steel. An extended charging handle 124 may be coupled to the bolt assembly 118 and may extend from the rear portion of the receiver 102. A magazine 120 may be insertable into the grip 104, and a magazine release 122 may be positioned near the trigger guard 108 to facilitate magazine removal and insertion.

[0027] The firearm 100 may be chambered for .22 LR, .21 Sharp, .17 HMR, .22 WMR, or combinations thereof. In some cases, the firearm 100 may be configured to receive various magazines that are each configured to retain different cartridges. For example, a first magazine may be configured to retain 22 LR cartridges and a second magazine may be configured to retain .21 Sharp, .17 HMR, or .22 WMR cartridges. The firearm 100 may incorporate a magazine disconnect feature, which is a safety mechanism that prevents the firearm 100 from firing when the magazine 120 is removed. In some cases, the firearm 100 may include a partial gas pedal or thumb pad to enhance user control and ergonomics during operation.

[0028] The components of the firearm 100 may be arranged in a linear configuration, with the barrel 110, the receiver 102, and the recoil post 116 aligned along a horizontal axis. This arrangement may contribute to balance, accuracy, and ergonomics of the firearm 100. In some cases, the firearm 100 may be disassembled using a 5 / 32 hex drive, which may allow for convenient field stripping and cleaning of the firearm 100.

[0029] Referring to FIGS. 2 and 3, the extended charging handle 124 may have a width greater than a width of the receiver 102. This increased width may offer advantages in terms of ergonomics and ease of use when manipulating the bolt assembly 118. The extended charging handle 124 may feature sides that are raked in at approximately 10 degrees. These angled sides may incorporate an aggressive texture pattern, which may enhance grip and control during operation. The textured surfaces of the extended charging handle 124 may provide improved traction for a user's fingers, reducing the likelihood of slippage during charging operations.

[0030] The extended charging handle 124 may incorporate a triple method charging design. This design may allow for three distinct methods of gripping and operating the extended charging handle 124. In a slingshot grip, the extended charging handle 124 may have an extended ring-like shape that allows users to grasp the extended charging handle 124 in a manner similar to aftermarket clamp-on halo rings. In a pinch grip, the textured, angled sides of the extended charging handle 124 may facilitate a secure pinch grip from the sides, where the extended charging handle 124 is gripped between a thumb and forefinger. In an overhand method, due to the extended width of the extended charging handle 124 relative to the receiver 102, users may be able to grasp the extended charging handle 124 from the top like a traditional slide using an overhand grip.

[0031] This versatile design may address a common complaint with internal bolt pistols, which may have small and sharp rear serrations that can be difficult to manipulate. The extended charging handle 124 may provide improved leverage and multiple gripping options, enhancing the overall user experience and ease of operation. In some cases, the receiver 102 may have a polished surface. This polished surface, in combination with the wider extended charging handle 124, may help prevent a user's hand from inadvertently gripping the receiver 102 during charging operations. The positioning of the rearward sight 114 and its relationship to the extended charging handle 124 may be designed to avoid interference during charging operations while maintaining proper sight alignment.

[0032] Referring to FIG. 4, a cutaway view of the firearm 100 exposes internal components within the receiver 102. A hammer 126 may be positioned within the receiver 102 and may be configured to rotate about a hammer axis 132. The hammer axis 132 defines a rotational pivot point for the hammer 126 during operation. A hammer spring 128 may be arranged to provide rotational force to the hammer 126, enabling a striking action for firing. The hammer spring 128 may be positioned inside a rear tang of the grip 104. In some cases, the hammer spring 128 may be loaded in a direction opposite to conventional designs, which may allow for efficient use of space within the grip 104 while maintaining proper functionality of a firing mechanism.

[0033] The recoil post 116 may be positioned at a rear portion of the receiver 102. A recoil post retaining pin 130 may extend through the recoil post 116 to secure the recoil post 116 in position within the receiver 102. Hammer spring 128 is retained by recoil post, which defines the hammer spring axis 129. The recoil post 116 may have a beak shape with a spring loaded configuration. In some cases, a hook on the recoil post 116 may engage a shelf on the receiver 102 to hold the receiver 102 down relative to the grip 104. The recoil post 116 may rotate on a hole that is drilled in rather than molded in, allowing for tight position control of a dimension from the hole to the shelf.

[0034] The receiver 102 may be secured to the grip 104 via a self-tensioning method. The recoil post 116 may be designed to pull a rear of the receiver 102 down when assembled. In some cases, a tensioning effect may be increased while the firearm 100 is firing. When the firearm 100 fires, the bolt assembly 118 may move rearward and load the recoil post 116, which may pull the receiver 102 rearward and downward. This self-tensioning arrangement may contribute to accuracy of the firearm 100.

[0035] A recoil assembly may include a dowel pin that is over molded or pressed into the grip 104. The dowel pin may be an off-the-shelf component that transfers recoil load from the receiver 102 to the grip 104. This arrangement may cause recoil forces to dissipate through metal-to-metal contact, reducing loading on plastic components of the grip 104.

[0036] The hammer spring 128 may provide high leverage against the hammer 126 at a hammer down position. In some cases, a point of contact between the hammer 126 and the hammer spring 128 may change through rotation of the hammer 126, creating a nonlinear force relationship. When the hammer 126 is in the hammer down position against the bolt assembly 118, a force of the hammer 126 against the bolt assembly 118 may be high. This high force may provide a self-tensioning lock up force that increases a force to pull the bolt assembly 118 out of battery.

[0037] The hammer 126 may have wire EDM sear surfaces. Wire EDM refers to wire electrical discharge machining, a process that may produce precise surface geometries. The wire EDM sear surfaces may contribute to a short, crisp trigger break, which may enhance trigger performance compared to molded-in sear surfaces.

[0038] Referring to FIG. 5, the hammer 126 is shown in an uncocked position within the receiver 102. The hammer 126 may include a hammer tail 134 that extends rearward from a main body of the hammer 126. The hammer tail 134 may interact with the hammer spring 128, which may be configured as a torsion spring. The hammer spring 128 may be positioned inside a rear tang of the grip 104 and may be loaded in a direction opposite to conventional hammer spring designs. This reverse-loaded configuration may allow for efficient use of space within the grip 104 while maintaining proper functionality of the firing mechanism.

[0039] The hammer 126 may have a uniquely shaped configuration that causes the hammer 126 to strike a firing pin at a grazing angle rather than perpendicular to an axis of the firing pin. Although this grazing angle may be geometrically inefficient, the hammer spring 128 may provide extremely high force against the hammer 126 due to a nonlinear relationship between a position of the hammer spring 128 and a force applied to the hammer 126. As the hammer 126 rotates about the hammer axis 132, a point of contact between the hammer 126 and the hammer spring 128 may change, resulting in varying leverage throughout the rotation. When the hammer 126 is in the uncocked position against the bolt assembly 118, the force of the hammer 126 against the bolt assembly 118 may be high, which may compensate for the geometric inefficiency of the grazing strike angle.

[0040] The firing pin may have a tapered design with a chamfered tail end. The tapered configuration and chamfered tail end may minimize drag and prevent the firing pin from nosing up during a firing sequence. When the hammer 126 strikes the firing pin at the grazing angle, the firing pin may tend to tip up within a bore of the bolt assembly 118. The chamfered tail end may reduce contact between the firing pin and bearing surfaces within the bolt assembly 118, thereby reducing friction and improving ignition efficiency.

[0041] The firing pin may be designed to be barely longer than a bolt face surface of the bolt assembly 118. This configuration may cause the hammer 126 to stop in the firing pin rather than hitting the bolt assembly 118. The grazing blow from the hammer 126 may be converted into forward force on the firing pin because the hammer 126 cannot travel further downward once the hammer 126 contacts the firing pin. The firing pin may have a round cross-section that is brought to a chisel tip for striking rimfire primers. The chisel tip geometry may provide a contact area suitable for compressing primer material without shearing brass of a cartridge case.

[0042] In some cases, a barrel sleeve may have a cut out for clearance with the hammer 126. The cut out may allow proper movement of the hammer 126 during a firing cycle without interference from the barrel sleeve.

[0043] A recoil spring of the bolt assembly 118 may be installed at a first length when outside the firearm 100 and may enter a second length condition when installed within the receiver 102, with the second length being slightly more compressed than the first length. A recoil pin may move from being tangent to a first position to being tangent to a second position on the recoil post 116. Travel of the recoil pin may be approximately half a diameter of the recoil pin. For example, for a recoil pin having a diameter of approximately 0.078 inches, the travel may be approximately 39 thousandths of an inch.

[0044] Due to the high lock up force provided by the hammer spring 128 configuration, a mass of the bolt assembly 118 may be reduced with no observable effect on operation of the firearm 100. In some cases, the bolt assembly 118 may be machined down to approximately 40 percent less mass while maintaining proper function. The high force of the hammer 126 against the bolt assembly 118 in the uncocked position may reduce reliance on inertia of the bolt assembly 118 to prevent early opening during firing.

[0045] Referring to FIG. 6, a rearward perspective view of the firearm 100 shows the recoil post 116 visible through an aperture defined in an upper portion of the receiver 102. The aperture may be positioned between the rearward sight 114 and the extended charging handle 124, allowing for visual confirmation of the presence and proper installation of the recoil post 116. The visibility of the recoil post 116 through the aperture may facilitate maintenance and inspection of the recoil post 116 without requiring complete disassembly of the firearm 100. The aperture may be designed to expose a portion of the recoil post 116 while balancing visibility with protection of internal components.

[0046] The receiver 102 may include a hammer track cut through a ceiling of the receiver 102. The hammer track may define a path through which the hammer 126 swings during operation of the firearm 100. The hammer track may be positioned to accommodate the hammer configuration and hammer spring arrangement described above, where the hammer 126 rotates through the hammer track to strike the firing pin.

[0047] The receiver 102 may be configured as a universal receiver for both 22 LR and Magnum versions of the firearm 100. A pocket may be defined on a top of the receiver 102 for an interrupter lug on a Magnum version of the firearm 100. On an LR version of the firearm 100, the pocket may be present but may not perform a function. This universal receiver design may allow the same receiver 102 to be used for both LR and Magnum configurations, reducing manufacturing complexity.

[0048] The receiver 102 may include an off-center recoil mechanism to accommodate a locking lug in a middle portion of the receiver 102 for the Magnum version. In some cases, the off-center recoil mechanism may be positioned to one side of a longitudinal axis of the receiver 102, leaving space in the middle for the locking lug to engage with a locking surface machined into the receiver 102. This arrangement may differ from other firearm designs where a recoil mechanism is positioned along a center axis of the receiver.

[0049] Referring to FIG. 7, a cutaway view of the firearm 100 shows the trigger 106 and a trigger return spring 136 within the receiver 102. The trigger 106 may be a flat-faced trigger that is 90 degrees at a point of break. This flat-faced configuration may provide a consistent and predictable trigger pull for improved shooting performance.

[0050] The trigger return spring 136 may be mounted above the trigger 106 and may interface with the trigger 106 to provide return force. The trigger return spring 136 may be a single spring that serves dual purposes, providing return force for both the trigger 106 and a trigger safety. This dual-purpose configuration may reduce a number of components within the firearm 100 while maintaining proper functionality of both the trigger 106 and the trigger safety.

[0051] A trigger pull weight of the firearm 100 may be adjustable by changing the trigger return spring 136. The trigger return spring 136 may be available in different strengths, allowing adjustment of the trigger pull weight between 3 pounds and higher weights. Different trigger return springs 136 with varying spring rates may be used to achieve different trigger pull weights, allowing for customization based on user preference or specific shooting applications.

[0052] To change the trigger return spring 136, a user may first remove an upper assembly of the firearm 100. With the trigger 106 and the trigger return spring 136 exposed, the user may push down on top coils of the trigger return spring 136 until the trigger return spring 136 disengages from a downward tooth of a trigger bar. The trigger return spring 136 may then be rocked slightly backward until the trigger return spring 136 can elongate behind the tooth. To insert a new trigger return spring 136, the process may be reversed, pushing the new trigger return spring 136 into a pocket at a slight angle, compressing the new trigger return spring 136 downward under the tooth, and then allowing the new trigger return spring 136 to elongate upward to be retained by the tooth.

[0053] Referring to FIG. 8, a perspective view of the bolt assembly 118 shows internal components and features. The bolt assembly 118 may include a bolt face 138 positioned at a forward end of the bolt assembly 118. An ejector 140 and a firing pin 142 may be integrated into the bolt face 138. The ejector 140 may be configured to eject spent cartridge casings from the firearm 100 after firing, while the firing pin 142 may be designed to strike a primer of a cartridge to initiate a firing sequence.

[0054] The extended charging handle 124 may be coupled to a rear portion of the bolt assembly 118. The extended charging handle 124 may allow a user to manually operate the bolt assembly 118, facilitating actions such as chambering a round or clearing a malfunction. On an LR version of the firearm 100, the extended charging handle 124 may be fixed to the bolt assembly 118 with two posts that go into counter bores. The extended charging handle 124 may snap into position via cam cuts in a back portion of the bolt assembly 118. When the extended charging handle 124 is installed, the extended charging handle 124 may go into position and snap into the counter bores, fixing the extended charging handle 124 to the bolt assembly 118.

[0055] The extended charging handle 124 may be configured as a one-piece snap-on ring design. This one-piece ring configuration may provide better purchase on the bolt assembly 118, which is an internal bolt design. Internal bolt pistols may have limited surfaces available for gripping because the bolt assembly 118 is positioned inside the receiver 102, allowing a user to grab only at a rear portion of the bolt assembly 118. The one-piece snap-on ring design of the extended charging handle 124 may address this limitation by providing an extended gripping surface that extends beyond a width of the receiver 102.

[0056] The bolt assembly 118 may incorporate a recoil assembly cross bar 144. The recoil assembly cross bar 144 may extend through the bolt assembly 118 perpendicular to a longitudinal axis of the bolt assembly 118. The recoil assembly cross bar 144 may serve as an anchor point for recoil springs or other components involved in cycling of the bolt assembly 118. A series of coil springs may be visible along a length of the bolt assembly 118. These springs may be housed within a main body of the bolt assembly 118 and may play a role in cycling and operation of the firearm 100. The springs may provide force to return the bolt assembly 118 to a forward position after firing. The components of the bolt assembly 118 may be arranged in a linear configuration, with the bolt face 138 positioned at a front, followed by an internal spring mechanism, with the extended charging handle 124 at a rear. This arrangement may facilitate smooth operation of the bolt assembly 118 within the receiver 102 of the firearm 100.

[0057] The firearm 100 may include a modular barrel system that allows for customization and barrel changes. A barrel may be removably coupled to the receiver 102, where the barrel and the receiver 102 utilize a locking system including an axial lug and a rotational key for repeatable barrel positioning. A set screw may be configured to bias the barrel against the receiver 102 to secure the barrel in a fixed position relative to the receiver 102.

[0058] The barrel may include a barrel core with a standard thread and a stanchion where an iron sight is mounted. Grooves may be positioned on either side of the barrel adjacent to the stanchion for barrel sleeve attachment. A barrel sleeve may be configured to slide onto the barrel from a chamber end of the barrel. The barrel sleeve may have detents at an end of slots that snap onto the stanchion of the barrel core. The barrel sleeve may be available in multiple profiles including round sleeves and square sleeves in different lengths such as seven inch and five inch configurations. The barrel sleeve may have a window on a top surface through which a caliber mark on the barrel shows. The caliber mark may be machined into the barrel rather than laser engraved, allowing the caliber mark to show through the barrel sleeve window regardless of which barrel sleeve profile is installed.

[0059] The receiver 102 may define an elliptical opening configured to receive the barrel. The elliptical opening may have a geometry that permits the barrel to be inserted in a first orientation and rotated to a second orientation in which the axial lug and the rotational key engage with corresponding features of the receiver 102. The barrel may have an elliptical cross-section at certain sections with round sections alternating with elliptical sections along a length of the barrel, creating interrupted sections for the locking interface. This interrupted geometry may allow the barrel to pass through the elliptical opening during insertion and then engage with locking features upon rotation.

[0060] The barrel may include a feed ramp, and the elliptical opening may be configured to permit the feed ramp to pass through the elliptical opening during insertion of the barrel into the receiver 102. When the barrel is positioned in the first orientation, the feed ramp may drop down through the elliptical opening. Once the feed ramp clears the elliptical opening, the barrel may be moved upward and forward to engage the locking features.

[0061] The axial lug may be positioned on the barrel and configured to engage with an axial pocket defined in the receiver 102 to constrain axial movement of the barrel relative to the receiver 102. The rotational key may be positioned on the barrel and configured to engage with a rotational pocket defined in the receiver 102 to constrain rotational movement of the barrel about a longitudinal axis of the barrel. The rotational key may be spaced apart from the axial lug along the longitudinal axis of the barrel.

[0062] The barrel may have vertical support through tangential contact from a barrel diameter to a top of the receiver 102 at two spaced locations. No vertical contact may be present in areas of the axial lug and the rotational key. The axial lug section may provide pure axial contact, while the rotational key section may provide pure roll contact. This arrangement may position vertical support points at extremities of the barrel engagement area, straddling the set screw location to provide stable barrel positioning.

[0063] A clearance between the rotational key and the rotational pocket may be approximately 2 thousandths of an inch on either side. This tight clearance may control barrel roll position, allowing the barrel to return to a consistent rotational position each time the barrel is installed. The tight rotational clearance may maintain point of impact and point of aim convergence when iron sights are split between the receiver 102 and the barrel.

[0064] A clearance between the axial lug and the axial pocket may be approximately 12 thousandths of an inch nominal. This clearance may allow the barrel to bias forward against a front of the axial pocket when the bolt assembly 118 pushes the barrel forward during operation. The forward bias arrangement may maintain consistent barrel position relative to the receiver 102 for proper feeding and headspacing.

[0065] The set screw may be positioned between the axial lug and the rotational key along the longitudinal axis of the barrel. This positioning may place the set screw in a balanced location relative to the vertical support points provided by the tangential contact areas. The set screw for barrel retention may use a same thread as an assembly screw that secures an upper assembly to the grip 104, allowing a same tool to be used for both fasteners during machining and assembly operations.

[0066] The barrel may include a flat surface configured to interface with the set screw. The flat surface may be oriented to resist rotation of the barrel when the set screw is tightened. The set screw may have a ring at a top of the set screw that bites into the flat surface on a barrel bottom to prevent loosening. The ring configuration may provide improved retention compared to a set screw bearing against a round surface, where the set screw would have two-point contact and may be more likely to loosen during operation.

[0067] Referring to FIG. 9, a magnum bolt assembly 218 may be configured for use with magnum rimfire cartridges in the firearm 100. The magnum bolt assembly 218 may include a delayed blowback system that provides positive case retention during firing of higher pressure cartridges such as .17 HMR and .22 WMR. The delayed blowback system may differ from straight blowback systems used in standard .22 LR firearms, where the bolt assembly 118 described above may operate without a locking mechanism.

[0068] The magnum bolt assembly 218 may include a magnum bolt body 219 that forms a main structural component of the magnum bolt assembly 218. A bolt face 238 may be positioned at a forward end of the magnum bolt body 219 and may be configured to interface with cartridges during operation. A push feed extractor 240 may be coupled to the magnum bolt body 219 and may be secured by an extractor pin 239. The push feed extractor 240 may increase an amount of support that a cartridge rim has during firing, minimizing a chance of blown cases with magnum rimfire ammunition. A firing pin 242 may extend through the magnum bolt body 219 and may be configured to strike a primer of a cartridge to initiate firing.

[0069] The delayed blowback system of the magnum bolt assembly 218 may include a locking block 250 and a carrier 252. The locking block 250 may be positioned within the magnum bolt body 219 and may be configured to engage a locking surface machined into the receiver 102 when the magnum bolt assembly 218 is in a locked position. The carrier 252 may interface with the locking block 250 through an angled ramp configuration. An angled interface between the locking block 250 and the carrier 252 may be configured to cause the locking block 250 to disengage from the locking surface when the carrier 252 moves rearward.

[0070] The magnum bolt assembly 218 may include a recoil guide rod 254 that extends rearward from the carrier 252 through the magnum bolt assembly 218. A recoil spring 258 may be disposed around the recoil guide rod 254 and may provide return force for cycling the magnum bolt assembly 218. A recoil spring stop nut 256 may be positioned at a rear portion of the recoil guide rod 254 to retain the recoil spring 258 in position. A recoil pin e-clip 264 may secure components of a recoil assembly within the magnum bolt assembly 218. A plurality of coil pins 266 may be used throughout the magnum bolt assembly 218 to secure various components in their respective positions.

[0071] An extended charging handle 224 may be coupled to a rear portion of the magnum bolt assembly 218. The extended charging handle 224 may be connected to the carrier 252 via a charge handle link 260. A charging handle retaining clip 262 may secure the extended charging handle 224 to the magnum bolt body 219. The charge handle link 260 may include a leg that is inserted into a hole on the extended charging handle 224, connecting the extended charging handle 224 to the carrier 252.

[0072] The magnum bolt assembly 218 may include an extra rod that goes through the magnum bolt body 219, where the extended charging handle 224 pulls back slightly to pull the rod rearward, which pulls the carrier 252 back to disengage the locking block 250 from the locking surface. Rearward movement of the extended charging handle 224 may cause the carrier 252 to move rearward and disengage the locking block 250 from the locking surface. This linkage arrangement may convert the rifle-style delayed blowback system into an internal bolt pistol configuration where the extended charging handle 224 is positioned at a rear of the magnum bolt assembly 218 rather than adjacent to the locking block 250.

[0073] The receiver 102 may include an off-center recoil mechanism to accommodate the locking block 250 in a middle portion of the receiver 102. On firearms with a center-mounted recoil mechanism, such as some existing rimfire pistol designs, the locking block 250 cannot be positioned in the middle of the receiver 102 because the recoil mechanism occupies that space. The off-center recoil mechanism of the firearm 100 may leave space in the middle of the receiver 102 for the locking block 250 to engage with the locking surface. A pocket may be defined on a top of the receiver 102 for an interrupter lug on the magnum version of the firearm 100, which may correspond to a location where the locking block 250 engages the receiver 102.

[0074] Referring to FIG. 10, an exploded perspective view of the magnum bolt assembly 218 shows the spatial arrangement of components that form the delayed blowback system. At a forward end of the magnum bolt assembly 218, the bolt face 238 may be positioned to interface with cartridges during operation. The push feed extractor 240 may be coupled to the bolt face 238 via the extractor pin 239. An extractor spring 241 may be positioned to provide biasing force for the push feed extractor 240, urging the push feed extractor 240 toward a cartridge extraction position. The firing pin 242 may extend through the magnum bolt body 219 and may be configured to strike a primer of a cartridge to initiate firing.

[0075] The magnum bolt body 219 may form a main structural component of the magnum bolt assembly 218 and may house internal mechanisms of the delayed blowback system. The locking block 250 may be positioned within the magnum bolt body 219 and may interface with the carrier 252. The locking block 250 and the carrier 252 may work together to provide delayed blowback action, with the locking block 250 engaging a locking surface in the receiver 102 when the magnum bolt assembly 218 is in battery.

[0076] The recoil guide rod 254 may extend rearward from the carrier 252 and may pass through the recoil spring 258. The recoil spring 258 may be disposed around the recoil guide rod 254 along a length of the recoil guide rod 254. The carrier 252 may be connected to the recoil guide rod 254 such that rearward movement of the carrier 252 compresses the recoil spring 258. The recoil guide rod 254 may extend through the magnum bolt assembly 218 along a longitudinal axis of the magnum bolt assembly 218. The recoil spring stop nut 256 may be positioned at a rear of the recoil guide rod 254 to retain the recoil spring 258 in place and prevent the recoil spring 258 from sliding off the recoil guide rod 254. The recoil pin e-clip 264 may secure components of a recoil assembly within the magnum bolt assembly 218.

[0077] The charge handle link 260 may connect the carrier 252 to the extended charging handle 224 positioned at a rear of the magnum bolt assembly 218. The extended charging handle 224 may allow manual operation of the magnum bolt assembly 218 and, through the charge handle link 260, may enable disengagement of the locking block 250 when the extended charging handle 224 is pulled rearward. The coil pins 266 may be used to secure various components within the magnum bolt assembly 218, maintaining proper alignment and retention of internal parts during operation.

[0078] Referring to FIG. 11, a perspective view of the magnum bolt assembly 218 shows internal components and features of the delayed blowback system. The magnum bolt assembly 218 may include the magnum bolt body 219 that forms a main structural element of the magnum bolt assembly 218. At a forward end of the magnum bolt assembly 218, the bolt face 238 may be positioned to interface with cartridges during operation. The push feed extractor 240 may be integrated into a bolt face area and may be secured by the extractor pin 239. The firing pin 242 may extend through the magnum bolt body 219 and may be visible at the bolt face 238.

[0079] The magnum bolt assembly 218 may incorporate the delayed blowback system including the locking block 250 and the carrier 252. The locking block 250 may be positioned within the magnum bolt body 219 and may be configured to engage a locking surface machined into the receiver 102 when the magnum bolt assembly 218 is in a locked position. The carrier 252 may interface with the locking block 250 through an angled ramp configuration. An angled interface between the locking block 250 and the carrier 252 may be configured to cause the locking block 250 to disengage from the locking surface when the carrier 252 moves rearward.

[0080] The recoil guide rod 254 may extend rearward from the carrier 252 and may support the recoil spring 258. The recoil spring 258 may be positioned along the recoil guide rod 254 and may provide return force for cycling the magnum bolt assembly 218. The recoil pin e-clip 264 may be visible and may serve to retain components of a recoil assembly within the magnum bolt assembly 218.

[0081] When the firearm 100 is fired, the locking block 250 may be pushed back against the locking surface of the receiver 102. The angled interface between the locking block 250 and the carrier 252 may push the locking block 250 downward as the locking block 250 is driven rearward. This downward movement of the locking block 250 may in turn push downward and backward on an angled ramp of the carrier 252, compressing the recoil spring 258. Upon the locking block 250 clearing the locking surface of the receiver 102, remaining energy from a fired round may push the magnum bolt body 219 rearward to complete a firing cycle.

[0082] Rearward movement of the extended charging handle 224 may cause the carrier 252 to move rearward and disengage the locking block 250 from the locking surface. When a user pulls rearward on the extended charging handle 224, the charge handle link 260 may transmit this motion to the carrier 252. As the carrier 252 moves rearward, the angled interface between the carrier 252 and the locking block 250 may allow the locking block 250 to move downward out of engagement with the locking surface, thereby unlocking the magnum bolt assembly 218 and permitting the magnum bolt body 219 to travel rearward for manual cycling operations.

[0083] Referring to FIG. 12, a cross-sectional view of a portion of the magnum bolt assembly 218 shows an arrangement of components that provide cartridge extraction and support functionality. The magnum bolt assembly 218 may include the magnum bolt body 219 that houses several components of the delayed blowback system. The bolt face 238 may be visible at a forward portion of the magnum bolt body 219 and may define a surface against which a cartridge head rests during firing.

[0084] The magnum bolt assembly 218 may further include a push feed extractor 240 configured to provide cartridge support during firing. The push feed extractor 240 may be positioned within the magnum bolt body 219 adjacent to the bolt face 238. The push feed extractor 240 may be biased by an extractor spring 241 and secured to the magnum bolt body 219 by an extractor pin. The extractor spring 241 may be arranged to urge the push feed extractor 240 toward a cartridge engagement position, where the push feed extractor 240 may grip a rim of a cartridge case for extraction after firing.

[0085] The push feed extractor 240 may differ from controlled round feed systems used in other rimfire handguns. In a controlled round feed system, an extractor may grip a cartridge rim as the cartridge is stripped from a magazine and may maintain grip throughout a feeding and firing cycle. In contrast, the push feed extractor 240 may allow a cartridge to be pushed into a chamber without the push feed extractor 240 initially gripping the cartridge rim. The push feed extractor 240 may then snap over the cartridge rim once the cartridge is fully chambered. This push feed configuration may increase an amount of support that the cartridge rim has during firing, which may minimize a chance of blown cases when firing magnum rimfire ammunition such as .17 HMR or .22 WMR cartridges.

[0086] The locking block 250 may be shown in an engaged position within the magnum bolt body 219. The spatial relationship between the push feed extractor 240, the extractor spring 241, and the locking block 250 within the magnum bolt body 219 may demonstrate how these components are arranged to provide both delayed blowback functionality and improved cartridge support. The push feed extractor 240 and extractor spring 241 may work together to provide cartridge extraction functionality while the locking block 250 interfaces with a locking surface of the receiver 102 to delay opening of the magnum bolt assembly 218 until chamber pressure has dropped to a safe level. This combination of push feed extraction and delayed blowback operation may provide reliable function with higher pressure magnum rimfire cartridges.

[0087] Referring to FIGS. 13A-13B, side cross-sectional views of the magnum bolt assembly 218 show the locking block 250 in locked and unlocked positions, respectively. In FIG. 13A, the locking block 250 may be shown in a locked position where the locking block 250 engages with a locking surface of the receiver 102. The carrier 252 may be positioned beneath the locking block 250 and may interface with the recoil guide rod 254, which extends rearward through the magnum bolt assembly 218. The charge handle link 260 may connect the carrier 252 to the extended charging handle 224, enabling manual operation of the magnum bolt assembly 218.

[0088] In FIG. 13B, the magnum bolt assembly 218 may be shown with the locking block 250 in an unlocked position. An arrow indicating displacement of locking block 251 may show a downward movement of the locking block 250 as the locking block 250 disengages from the locking surface of the receiver 102. An arrow indicating displacement of charging handle 225 may indicate a rearward movement of the extended charging handle 224 during an unlocking operation. When the extended charging handle 224 is pulled rearward, the charge handle link 260 may pull the carrier 252 rearward, which may in turn cause the locking block 250 to move downward along an angled ramp interface with the carrier 252, thereby disengaging the locking block 250 and allowing the magnum bolt body 219 to travel rearward.

[0089] The extended charging handle 224 may be coupled to the magnum bolt body 219 via a sliding connection that permits limited rearward movement of the extended charging handle 224 relative to the magnum bolt body 219. The sliding connection may include bosses on the extended charging handle 224 that interface with slots defined in the magnum bolt body 219. The bosses may be round protrusions that extend from the extended charging handle 224 and may be received within elongated slots formed in the magnum bolt body 219. This sliding connection may allow the extended charging handle 224 to travel rearward a limited distance relative to the magnum bolt body 219 before the magnum bolt body 219 begins to move rearward.

[0090] When a user pulls rearward on the extended charging handle 224, the extended charging handle 224 may first move rearward within the slots of the magnum bolt body 219 as indicated by the arrow indicating displacement of charging handle 225. This initial rearward movement of the extended charging handle 224 may be transmitted through the charge handle link 260 to the carrier 252. As the carrier 252 moves rearward, the angled interface between the carrier 252 and the locking block 250 may cause the locking block 250 to move downward as indicated by the arrow indicating displacement of locking block 251. Once the locking block 250 clears the locking surface of the receiver 102, continued rearward force on the extended charging handle 224 may cause the magnum bolt body 219 to travel rearward along with the extended charging handle 224 for manual cycling of the magnum bolt assembly 218.

[0091] The arrangement of the locking block 250 and the carrier 252 may provide a delayed blowback system where the angled interface between these components controls timing of bolt unlocking during a firing cycle. This configuration may allow the extended charging handle 224, positioned at a rear of the magnum bolt assembly 218, to actuate a locking mechanism located at a front of the magnum bolt assembly 218 through a mechanical linkage provided by the charge handle link 260 and the carrier 252. The sliding connection between the extended charging handle 224 and the magnum bolt body 219 may provide the initial travel distance for the extended charging handle 224 to disengage the locking block 250 before the magnum bolt body 219 begins rearward travel.

[0092] Referring to FIGS. 14A-14B, isolated views of the locking block 250 and the carrier 252 show the mechanical interaction between these two components in locked and unlocked positions. The isolated views may illustrate the relationship between the locking block 250 and the carrier 252 without surrounding components of the magnum bolt assembly 218, providing a clear depiction of the interface geometry that controls locking and unlocking operations.

[0093] An arrow indicating displacement of locking block 251 may show a direction of movement of the locking block 250 as the locking block 250 transitions between locked and unlocked states. An arrow indicating displacement of charging handle 225 may indicate a corresponding movement direction associated with charging handle operation. The locking block 250 may interface with an angled ramp surface on the carrier 252. When the locking block 250 is pushed rearward against a locking surface of the receiver 102, the angled interface may cause the locking block 250 to move downward as indicated by the arrow indicating displacement of locking block 251.

[0094] The downward movement of the locking block 250 may in turn push downward and backward on the angled ramp of the carrier 252. The relationship between the locking block 250 and the carrier 252 may demonstrate a delayed blowback mechanism where the locking block 250 clears the locking surface before a bolt body can travel rearward. The arrows indicating displacement of locking block 251 and displacement of charging handle 225 may illustrate coordinated movement of these components during an unlocking sequence, showing how manual operation of a charging handle results in disengagement of the locking block 250 from a locked position.

[0095] The angled interface between the locking block 250 and the carrier 252 may convert rearward motion of the carrier 252 into downward motion of the locking block 250. This cam-like action may allow the locking block 250 to be driven out of engagement with the locking surface of the receiver 102 through rearward force applied to the carrier 252. The geometry of the angled ramp may determine a mechanical advantage and timing relationship between carrier movement and locking block disengagement. The isolated views may show that the locking block 250 and the carrier 252 form a self-contained locking mechanism that responds to rearward force on the carrier 252 by releasing the locking block 250 from engagement with the receiver 102.

[0096] Referring to FIG. 15A, a magazine 300 may be configured for use with the firearm 100. The magazine 300 may include an injection molded magazine body 302 configured to retain rimfire cartridges in an angled orientation. The injection molded magazine body 302 may form a primary structure for retaining cartridges within the magazine 300. A follower 304 may be positioned within the injection molded magazine body 302 and may be configured to support and feed cartridges upward during operation. The follower 304 may be configured to pivot to support the angled rimfire cartridges, allowing the follower 304 to accommodate the natural tendency of rimfire cartridges to angle themselves due to a rim of the cartridges being wider than a rest of a cartridge body.

[0097] A stamped backer plate 310 may be attached to the injection molded magazine body 302. The stamped backer plate 310 may be positioned at a rear portion of the injection molded magazine body 302 and may provide a wear-resistant surface. The stamped backer plate 310 may include a plurality of round holes along sides of the stamped backer plate 310 that interface with corresponding round posts on the injection molded magazine body 302 to secure the stamped backer plate 310 in position. A base plate 306 may be positioned at a bottom of the magazine 300. The base plate 306 may feature a textured surface with a plurality of raised elements to facilitate grip during magazine insertion and removal.

[0098] The magazine 300 may be built around a 1911 size footprint to accommodate longer magnum cartridges while using a common magazine footprint. A maximum length of .22 WMR and .17 HMR cartridges may be 1.350 inches and 1.365 inches respectively, which may be longer than a maximum cartridge length of .45 ACP at 1.275 inches that a 1911 magazine was designed around. The angled cartridge orientation within the injection molded magazine body 302 may accommodate the longer cartridge length while maintaining the 1911 magazine footprint. The magazine 300 may be compatible with 1911 magazine holders and pouches, allowing users to utilize existing 1911 magazine carrying equipment with the firearm 100.

[0099] Referring to FIG. 15B, a perspective view of the magazine 300 shows the injection molded magazine body 302 with a cartridge positioned on the follower 304. The injection molded magazine body 302 may form a main housing structure for retaining cartridges within the magazine 300. The follower 304 may be positioned within the injection molded magazine body 302 and may be visible near a top portion of the magazine 300, where a cartridge can be seen resting on the follower 304. The follower 304 may be configured to move vertically within the injection molded magazine body 302 as cartridges are loaded and fed from the magazine 300.

[0100] The follower 304 may include protrusions extending from sides of the follower 304. The protrusions may be configured to interface with slots defined in the injection molded magazine body 302 to guide movement of the follower 304 during loading and unloading. The injection molded magazine body 302 may include elongated slots along sides of the injection molded magazine body 302 that receive the protrusions of the follower 304. As cartridges are loaded into the magazine 300, the follower 304 may move downward within the injection molded magazine body 302, with the protrusions traveling along the slots to maintain proper alignment of the follower 304. During feeding operations, the follower 304 may move upward to push cartridges toward feed lips of the magazine 300, with the protrusions sliding along the slots to guide the upward movement of the follower 304.

[0101] The stamped backer plate 310 may be attached to one side of the injection molded magazine body 302. The stamped backer plate 310 may feature a plurality of holes along sides of the stamped backer plate 310 that interface with corresponding posts on the injection molded magazine body 302 to secure the stamped backer plate 310 in position. The base plate 306 may be positioned at a bottom of the magazine 300 and may serve to close a lower end of the injection molded magazine body 302 while retaining internal components such as a follower spring within the magazine 300.

[0102] Referring to FIG. 15C, a cross-sectional view of the magazine 300 shows internal components and their arrangement within the injection molded magazine body 302. The injection molded magazine body 302 may form an outer structure of the magazine 300 and may be configured to retain cartridges in an angled orientation. The angled orientation may take advantage of a natural tendency of rimfire cartridges to angle themselves due to a rim of the cartridges being wider than a rest of a cartridge body.

[0103] The stamped backer plate 310 may be attached to a rear of the injection molded magazine body 302. The stamped backer plate 310 may provide a thin, wear-resistant surface compared to a comparable injection molded plastic backer. The stamped backer plate 310 may interface with the injection molded magazine body 302 through a connection where flared sides of the injection molded magazine body 302 are compressed inward and a plurality of round posts interface with a plurality of round holes on sides of the stamped backer plate 310.

[0104] A follower spring 308 may be positioned within the injection molded magazine body 302. The follower spring 308 may provide upward force to bias cartridges toward a top of the magazine 300. A follower spring plunger 312 may be positioned at an upper end of the follower spring 308. The follower spring plunger 312 may interface with the follower 304 to support angled rounds of ammunition within the magazine 300. The base plate 306 may be positioned at a bottom of the magazine 300 and may serve to retain internal components within the injection molded magazine body 302.

[0105] The injection molded magazine body 302 may include internal lips positioned near the stamped backer plate 310. The internal lips may be configured to control positioning of rimfire cartridges to minimize rim-lock. Rim-lock may be an issue common with rimmed cartridges, both centerfire and rimfire, where a rim of one cartridge may become positioned behind a rim of an adjacent cartridge, preventing proper feeding. The internal lips may control positioning of rounds depending on how loaded or unloaded the magazine 300 is, helping to prevent the rims of adjacent cartridges from overlapping in a manner that would cause rim-lock during feeding operations.

[0106] Referring to FIG. 15D, an exploded view of the magazine 300 shows the spatial arrangement of components that form the magazine assembly. The injection molded magazine body 302 may form a main housing structure of the magazine 300 and may be configured to retain cartridges in a stacked arrangement. The injection molded magazine body 302 may feature viewing windows along a side of the injection molded magazine body 302 that allow visual confirmation of an ammunition level within the magazine 300.

[0107] The injection molded magazine body 302 may include a plurality of raised posts positioned along sides of the injection molded magazine body 302. The plurality of raised posts may be round protrusions that extend outward from exterior surfaces of the injection molded magazine body 302. The stamped backer plate 310 may include a plurality of holes configured to interface with the plurality of raised posts to secure the stamped backer plate 310 to the injection molded magazine body 302. The plurality of holes may be round apertures formed in the stamped backer plate 310 that correspond in position and size to the plurality of raised posts on the injection molded magazine body 302.

[0108] The injection molded magazine body 302 may include sides configured to flair outward. The outward flair of the sides may be an intentional design feature of the injection molded magazine body 302 that facilitates assembly with the stamped backer plate 310. When the stamped backer plate 310 is installed onto the injection molded magazine body 302, installation of the stamped backer plate 310 may compress the sides inward to engage the plurality of raised posts with the plurality of holes. The compression of the flared sides inward may cause the plurality of raised posts to align with and enter the plurality of holes in the stamped backer plate 310, thereby locking the stamped backer plate 310 and the injection molded magazine body 302 together.

[0109] The follower 304 may be positioned within the injection molded magazine body 302 and may be configured to move vertically within the injection molded magazine body 302 to push cartridges upward toward feed lips during operation. The follower 304 may include protrusions on sides of the follower 304 that interface with slots along sides of the injection molded magazine body 302, providing guidance as the follower 304 moves through a range of motion during loading and unloading. The base plate 306 may be positioned at a bottom of the magazine 300 and may provide a foundation for the magazine assembly. The base plate 306 may feature a textured surface with a plurality of ridges that may assist with magazine removal from the firearm 100.

[0110] The firearm 100 may include an ambidextrous safety system configured to provide user-selectable safe and fire modes from either side of the firearm 100. The ambidextrous safety system may include a strong side safety lever and a weak side safety lever that are mechanically linked to rotate together. The strong side safety lever may include a shaft that extends through the grip 104 from one side to an opposite side. The weak side safety lever may attach to the shaft via a screw and a keyway shape connection. The keyway shape connection may provide rotational coupling between the weak side safety lever and the shaft such that rotation of either safety lever causes corresponding rotation of the other safety lever.

[0111] The grip 104 may include molded pockets configured to house detent components for the ambidextrous safety system. A first molded pocket may be configured to receive a spring and a ball bearing that form a detent mechanism. The detent mechanism may provide positive tactile feedback when the safety is moved between safe and fire positions. The detent mechanism may include an eighth inch diameter spring positioned within a hole having a diameter of approximately 130 thousandths of an inch. An eighth inch diameter ball bearing may be positioned above the spring within the hole. The spring may bias the ball bearing outward against a surface of the safety lever, and the ball bearing may engage detent features on the safety lever to provide distinct click positions corresponding to safe and fire modes.

[0112] The grip 104 may include an anti-rotational stop that interfaces with the safety lever to define rotational limits of the safety. The anti-rotational stop may be tapered down at an angle. The tapered configuration of the anti-rotational stop may position a top stop surface at a location that defines a maximum rotational position of the safety lever. When the safety lever rotates to the fire position, the safety lever may bottom out against the anti-rotational stop. The anti-rotational stop may be positioned far from a rotational axis of the safety lever, providing stable rotational constraint.

[0113] The ambidextrous safety system may include safety paddles that are configured to be shallow in profile. Each safety paddle may have a thickness of approximately 50 thousandths of an inch. The shallow profile of the safety paddles may allow the safety paddles to sit within pockets formed in the grip 104 adjacent to sweep cuts. The sweep cuts may be contoured surfaces on the grip 104 that allow a user's knuckle to rest against the grip 104 while operating the safety. When a user thumbs the safety paddle downward to move from safe to fire mode, the user's knuckle may rest in the sweep cut while the safety paddle moves within the adjacent pocket. The shallow safety paddle may move inside the user's hand without causing interference or discomfort during operation. Clause 21. A firearm comprising: a receiver; a grip extending from the receiver; a barrel coupled to the receiver; a bolt assembly housed within the receiver; and an extended charging handle coupled to the bolt assembly, wherein the extended charging handle has a width greater than a width of the receiver.

[0114] The ambidextrous safety system may include fire indicator elements that provide visual indication of the fire mode. Each fire indicator may be a red ball having a diameter of approximately 157 thousandths of an inch. The red ball may be positioned within a hole in the grip 104 in an interference fit configuration. When the safety is in the fire position, the red ball may be visible to indicate that the firearm 100 is ready to fire. When the safety is moved to the safe position, the safety paddle may rotate to cover the red ball, obscuring the fire indicator from view. The covering of the red ball by the safety paddle may provide both visual confirmation of the safe mode and protection of the fire indicator element.

[0115] The detent mechanism may produce a distinct click sensation when the safety is moved between positions. As the safety lever rotates from the safe position toward the fire position, the ball bearing may ride along a surface of the safety lever until the ball bearing engages a detent feature corresponding to the fire position. The spring-loaded ball bearing may snap into the detent feature, producing tactile and audible feedback that confirms the safety has reached the fire position. Similarly, when the safety lever is rotated from the fire position toward the safe position, the ball bearing may disengage from the fire position detent feature and engage a detent feature corresponding to the safe position, again producing tactile and audible feedback. The metal-to-metal contact between the ball bearing and the safety lever surfaces may provide consistent and positive detent action.

[0116] The following clauses illustrated example subject matter described herein.

[0117] Clause 1. A firearm comprising: a receiver; a barrel removably coupled to the receiver, wherein the barrel and the receiver utilize a locking system comprising an axial lug and a rotational key for repeatable barrel positioning; a bolt assembly housed within the receiver; and a set screw configured to bias the barrel against the receiver to secure the barrel in a fixed position relative to the receiver.

[0118] Clause 2. The firearm of clause 1, wherein the axial lug is positioned on the barrel and configured to engage with an axial pocket defined in the receiver to constrain axial movement of the barrel relative to the receiver.

[0119] Clause 3. The firearm of clause 2, wherein the rotational key is positioned on the barrel and configured to engage with a rotational pocket defined in the receiver to constrain rotational movement of the barrel about a longitudinal axis of the barrel.

[0120] Clause 4. The firearm of clause 3, wherein the rotational key is spaced apart from the axial lug along the longitudinal axis of the barrel.

[0121] Clause 5. The firearm of clause 4, wherein the set screw is positioned between the axial lug and the rotational key along the longitudinal axis of the barrel.

[0122] Clause 6. The firearm of clause 1, wherein the barrel includes a flat surface configured to interface with the set screw, the flat surface being oriented to resist rotation of the barrel when the set screw is tightened.

[0123] Clause 7. The firearm of clause 1, wherein the receiver defines an elliptical opening configured to receive the barrel, the elliptical opening having a geometry that permits the barrel to be inserted in a first orientation and rotated to a second orientation in which the axial lug and the rotational key engage with corresponding features of the receiver.

[0124] Clause 8. The firearm of clause 7, wherein the barrel includes a feed ramp, and wherein the elliptical opening is configured to permit the feed ramp to pass through the elliptical opening during insertion of the barrel into the receiver.

[0125] Clause 9. The firearm of clause 1, further comprising a barrel sleeve configured to slide onto the barrel from a chamber end of the barrel.

[0126] Clause 10. A firearm comprising: a receiver; a grip extending from the receiver; a barrel coupled to the receiver; a bolt assembly housed within the receiver, the bolt assembly comprising a locking block and a carrier, wherein the locking block is configured to engage a locking surface of the receiver when the bolt assembly is in a locked position, and wherein an angled interface between the locking block and the carrier is configured to cause the locking block to disengage from the locking surface when the carrier moves rearward; and a charging handle coupled to the bolt assembly and connected to the carrier via a charge handle link, wherein rearward movement of the charging handle causes the carrier to move rearward and disengage the locking block from the locking surface.

[0127] Clause 11. The firearm of clause 10, wherein the charging handle is coupled to a bolt body of the bolt assembly via a sliding connection that permits limited rearward movement of the charging handle relative to the bolt body.

[0128] Clause 12. The firearm of clause 11, wherein the sliding connection comprises bosses on the charging handle that interface with slots defined in the bolt body.

[0129] Clause 13. The firearm of clause 10, further comprising a recoil spring disposed around a recoil guide rod, wherein the carrier is connected to the recoil guide rod such that rearward movement of the carrier compresses the recoil spring.

[0130] Clause 14. The firearm of clause 13, wherein the recoil guide rod extends through the bolt assembly along a longitudinal axis of the bolt assembly.

[0131] Clause 15. The firearm of clause 10, wherein the bolt assembly further comprises a push feed extractor configured to provide cartridge support during firing.

[0132] Clause 16. The firearm of clause 15, wherein the push feed extractor is biased by an extractor spring and secured to a bolt body of the bolt assembly by an extractor pin.

[0133] Clause 17. A magazine for a firearm, the magazine comprising: an injection molded magazine body configured to retain rimfire cartridges in an angled orientation; a stamped backer plate attached to the injection molded magazine body, wherein the injection molded magazine body comprises a plurality of raised posts and the stamped backer plate comprises a plurality of holes configured to interface with the plurality of raised posts to secure the stamped backer plate to the injection molded magazine body; and a follower positioned within the injection molded magazine body, the follower configured to pivot to support the angled rimfire cartridges.

[0134] Clause 18. The magazine of clause 17, wherein the injection molded magazine body comprises sides configured to flair outward, and wherein installation of the stamped backer plate compresses the sides inward to engage the plurality of raised posts with the plurality of holes.

[0135] Clause 19. The magazine of clause 17, wherein the follower comprises protrusions extending from sides of the follower, the protrusions configured to interface with slots defined in the injection molded magazine body to guide movement of the follower during loading and unloading.

[0136] Clause 20. The magazine of clause 19, wherein the injection molded magazine body comprises internal lips positioned near the stamped backer plate, the internal lips configured to control positioning of the rimfire cartridges to minimize rim-lock.

[0137] Clause 21. A firearm comprising: a receiver; a grip extending from the receiver; a barrel coupled to the receiver; a bolt assembly housed within the receiver; and an extended charging handle coupled to the bolt assembly. wherein the extended charging handle has a width greater than a width of the receiver.

[0138] Clause 22. The firearm of clause 21, wherein the extended charging handle comprises textured surfaces for enhanced grip.

[0139] Clause 23. The firearm of clause 21, wherein the barrel is removably coupled to the receiver via a set screw.

[0140] Clause 24. The firearm of clause 23, further comprising a barrel sleeve that slides onto the barrel from a chamber end of the barrel.

[0141] Clause 25. The firearm of clause 21, further comprising a hammer positioned within the receiver and a hammer spring arranged to provide rotational force to the hammer.

[0142] Clause 26. The firearm of clause 25, wherein the hammer comprises a hammer tail that extends rearward from a main body of the hammer.

[0143] Clause 27. The firearm of any one of clauses 21 through 26, further comprising a recoil post positioned at a rear portion of the receiver, wherein the recoil post is visible through an aperture defined in the receiver.

[0144] Clause 28. A firearm comprising: a receiver; a grip extending from the receiver; a barrel removably coupled to the receiver; a bolt assembly housed within the receiver; a hammer positioned within the receiver; and a hammer spring arranged to provide rotational force to the hammer, wherein the hammer spring is positioned inside a rear tang of the grip.

[0145] Clause 29. The firearm of clause 28, wherein the hammer comprises a hammer tail that extends rearward from a main body of the hammer.

[0146] Clause 30. The firearm of clause 29, wherein the hammer spring is a torsion spring arranged to interact with the hammer tail.

[0147] Clause 31. The firearm of clause 28, wherein the barrel is removably coupled to the receiver via a set screw.

[0148] Clause 32. The firearm of clause 31, further comprising a barrel sleeve that slides onto the barrel from a chamber end of the barrel.

[0149] Clause 33. The firearm of clause 32, wherein the barrel and receiver utilize a locking system comprising an axial lug and a rotational key for repeatable barrel positioning.

[0150] Clause 34. The firearm of any one of clauses 28 through 33, further comprising an extended charging handle coupled to the bolt assembly, wherein the extended charging handle has a width greater than a width of the receiver and comprises textured surfaces for enhanced grip.

[0151] Clause 35. A method of operating a firearm, the method comprising: grasping an extended charging handle coupled to a bolt assembly of the firearm, wherein the extended charging handle has a width greater than a width of a receiver of the firearm; and manipulating the extended charging handle to cycle the bolt assembly.

[0152] Clause 36. The method of clause 35, wherein grasping the extended charging handle comprises gripping textured surfaces on the extended charging handle.

[0153] Clause 37. The method of clause 35, wherein manipulating the extended charging handle comprises using one of a slingshot grip, a pinch grip, or an overhand grip.

[0154] Clause 38. The method of clause 35, further comprising: removing a barrel from the firearm by loosening a set screw; and replacing the removed barrel with a different barrel.

[0155] Clause 39. The method of clause 38, further comprising sliding a barrel sleeve onto the different barrel from a chamber end of the different barrel.

[0156] Clause 40. The method of any one of clauses 35 through 39, further comprising adjusting a trigger pull weight of the firearm by changing a trigger spring.

[0157] While the disclosure has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore, it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the disclosure, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,”“an,”“at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and / or “a portion” is used the item may include a portion and / or the entire item unless specifically stated to the contrary.

Examples

Embodiment Construction

[0023] For purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the disclosure is intended by the illustration and description of certain embodiments of the disclosure. In addition, any alterations and / or modifications of the illustrated and / or described embodiment(s) are contemplated as being within the scope of the present disclosure. Further, any other applications of the principles of the disclosure, as illustrated and / or described herein, as would normally occur to one skilled in the art to which the disclosure pertains, are contemplated as being within the scope of the present disclosure.

[0024]Referring to FIG. 1, a firearm 100 may include a receiver 102 that forms a main body of the firearm 100. The receiver 102 may be constructed from case hardened steel,...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 746,497, titled RIMFIRE HANDGUN, filed January 17, 2025, the entirety of which is hereby incorporated by reference herein.TECHNICAL FIELD

[0002] The present disclosure relates to firearms, and more particularly to a semi-automatic rimfire handgun with a modular barrel system, an optional delayed blowback bolt assembly, and an optional magazine configured to accommodate magnum rimfire cartridges.BACKGROUND

[0003] Semi-automatic rimfire handguns have gained popularity among recreational shooters, competitive marksmen, and firearms enthusiasts due to their compact designs, manageable recoil characteristics, and relatively inexpensive ammunition. These firearms typically employ internal bolt mechanisms that cycle within a receiver to chamber, fire, and eject rimfire cartridges. Various approaches have been developed for coupling barrels to receivers, with some designs utilizing press-fit arrangements that provide rigid connections but limit user serviceability, while other designs employ set screws or similar fasteners that permit barrel removal but may not consistently maintain barrel alignment after reassembly. Existing rimfire handgun platforms designed for standard .22 LR cartridges often utilize straight blowback operating systems, which rely on bolt mass and spring tension to control the firing cycle. However, higher-pressure magnum rimfire cartridges such as .22 WMR and .17 HMR present challenges for straight blowback systems due to the increased chamber pressures and the need for positive case retention during firing. Magazine designs for rimfire firearms must accommodate the rimmed nature of rimfire cartridges, which can lead to feeding issues such as rim-lock when cartridge rims overlap improperly within the magazine body.SUMMARY

[0004] In some examples, the disclosure describes a firearm that includes a receiver, a barrel removably coupled to the receiver, a bolt assembly housed within the receiver, and a set screw configured to bias the barrel against the receiver to secure the barrel in a fixed position relative to the receiver. The barrel and the receiver utilize a locking system that includes an axial lug and a rotational key for repeatable barrel positioning.

[0005] In some examples, the disclosure describes a firearm that includes a receiver, a grip extending from the receiver, a barrel coupled to the receiver, a bolt assembly housed within the receiver, and a charging handle coupled to the bolt assembly and connected to a carrier via a charge handle link. The bolt assembly includes a locking block and the carrier. The locking block is configured to engage a locking surface of the receiver when the bolt assembly is in a locked position. An angled interface between the locking block and the carrier is configured to cause the locking block to disengage from the locking surface when the carrier moves rearward. Rearward movement of the charging handle causes the carrier to move rearward and disengage the locking block from the locking surface.

[0006] In some examples, the disclosure describes a magazine for a firearm that includes an injection molded magazine body configured to retain rimfire cartridges in an angled orientation, a stamped backer plate attached to the injection molded magazine body, and a follower positioned within the injection molded magazine body. The injection molded magazine body includes a plurality of raised posts and the stamped backer plate includes a plurality of holes configured to interface with the plurality of raised posts to secure the stamped backer plate to the injection molded magazine body. The follower is configured to pivot to support the angled rimfire cartridges.

[0007] The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure and are not restrictive.BRIEF DESCRIPTION OF FIGURES

[0008] The disclosure can be understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings.

[0009] FIGS. 1A and 1B are a conceptual diagram illustrating views of an example firearm.

[0010] FIGS. 2 and 3 are conceptual diagrams illustrating a rearward perspective view of the firearm of FIG. 1 showing an extended charging handle.

[0011] FIG. 4 is a conceptual diagram illustrating a cutaway view of the firearm of FIG. 1 exposing internal components.

[0012] FIG. 5 is a conceptual diagram illustrating a cutaway view of the firearm of FIG. 1 showing a hammer in an uncocked position.

[0013] FIG. 6 is a conceptual diagram illustrating a rearward perspective view of the firearm of FIG. 1 showing an exposed recoil post.

[0014] FIG. 7 is a conceptual diagram illustrating a cutaway view of the firearm of FIG. 1 showing a trigger mechanism and a trigger return spring.

[0015] FIG. 8 is a conceptual diagram illustrating a perspective view of a bolt assembly of the firearm of FIG. 1.

[0016] FIG. 9 is a conceptual diagram illustrating a cutaway perspective view of a magnum bolt assembly.

[0017] FIG. 10 is a conceptual diagram illustrating an exploded perspective view of the magnum bolt assembly of FIG. 9.

[0018] FIG. 11 is a conceptual diagram illustrating a perspective view of the magnum bolt assembly of FIG. 9 showing internal components.

[0019] FIG. 12 is a conceptual diagram illustrating a cross-sectional view of a portion of the magnum bolt assembly of FIG. 9.

[0020] FIGS. 13A and 13B are conceptual diagrams illustrating side cross-sectional views of the magnum bolt assembly of FIG. 9 showing a locking block in locked and unlocked positions.

[0021] FIGS. 14A and 14B are conceptual diagrams illustrating isolated views of a locking block and a carrier in locked and unlocked positions.

[0022] FIGS. 15A through 15C are a conceptual diagram illustrating various views of a magazine configured to retain magnum rimfire cartridges.DETAILED DESCRIPTION

[0023] For purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the disclosure is intended by the illustration and description of certain embodiments of the disclosure. In addition, any alterations and / or modifications of the illustrated and / or described embodiment(s) are contemplated as being within the scope of the present disclosure. Further, any other applications of the principles of the disclosure, as illustrated and / or described herein, as would normally occur to one skilled in the art to which the disclosure pertains, are contemplated as being within the scope of the present disclosure.

[0024] Referring to FIG. 1, a firearm 100 may include a receiver 102 that forms a main body of the firearm 100. The receiver 102 may be constructed from case hardened steel, providing durability and strength to the firearm 100. A grip 104 may extend downward from the receiver 102, providing a holding surface for a user. The grip 104 may be constructed from a high-strength polymer, such as a polyamide, for example, Grivory GV available from EMS-CHEMIE, Sumter, South Carolina, which offers a balance of durability and weight reduction. The grip 104 may be designed with a Savage Arms 1911 style angle, providing a familiar and ergonomic feel for users. In some cases, the grip 104 may be designed to be compatible with 1911 grip panels, allowing for customization of the grip surface. The firearm 100 may include an integrated accessory rail 105 for attaching accessories such as lights or lasers.

[0025] A trigger 106 may be positioned within a trigger guard 108, which is located below the receiver 102. A barrel 110 may be coupled to the receiver 102 and may extend forward from the receiver 102. The barrel 110 may be constructed from 4140 steel. A forward sight 112 may be mounted near a front end of the barrel 110, while a rearward sight 114 may be positioned on a rear portion of the receiver 102 to facilitate aiming. The rearward sight 114 may be mounted using a dovetail system, which may allow for adjustment or replacement of the rearward sight 114 to suit user preferences.

[0026] As further shown in FIG. 1, a recoil post 116 may be positioned at a rear of the receiver 102. A bolt assembly 118 may be housed within the receiver 102. The bolt assembly 118 may be fabricated from 4140 steel. An extended charging handle 124 may be coupled to the bolt assembly 118 and may extend from the rear portion of the receiver 102. A magazine 120 may be insertable into the grip 104, and a magazine release 122 may be positioned near the trigger guard 108 to facilitate magazine removal and insertion.

[0027] The firearm 100 may be chambered for .22 LR, .21 Sharp, .17 HMR, .22 WMR, or combinations thereof. In some cases, the firearm 100 may be configured to receive various magazines that are each configured to retain different cartridges. For example, a first magazine may be configured to retain 22 LR cartridges and a second magazine may be configured to retain .21 Sharp, .17 HMR, or .22 WMR cartridges. The firearm 100 may incorporate a magazine disconnect feature, which is a safety mechanism that prevents the firearm 100 from firing when the magazine 120 is removed. In some cases, the firearm 100 may include a partial gas pedal or thumb pad to enhance user control and ergonomics during operation.

[0028] The components of the firearm 100 may be arranged in a linear configuration, with the barrel 110, the receiver 102, and the recoil post 116 aligned along a horizontal axis. This arrangement may contribute to balance, accuracy, and ergonomics of the firearm 100. In some cases, the firearm 100 may be disassembled using a 5 / 32 hex drive, which may allow for convenient field stripping and cleaning of the firearm 100.

[0029] Referring to FIGS. 2 and 3, the extended charging handle 124 may have a width greater than a width of the receiver 102. This increased width may offer advantages in terms of ergonomics and ease of use when manipulating the bolt assembly 118. The extended charging handle 124 may feature sides that are raked in at approximately 10 degrees. These angled sides may incorporate an aggressive texture pattern, which may enhance grip and control during operation. The textured surfaces of the extended charging handle 124 may provide improved traction for a user's fingers, reducing the likelihood of slippage during charging operations.

[0030] The extended charging handle 124 may incorporate a triple method charging design. This design may allow for three distinct methods of gripping and operating the extended charging handle 124. In a slingshot grip, the extended charging handle 124 may have an extended ring-like shape that allows users to grasp the extended charging handle 124 in a manner similar to aftermarket clamp-on halo rings. In a pinch grip, the textured, angled sides of the extended charging handle 124 may facilitate a secure pinch grip from the sides, where the extended charging handle 124 is gripped between a thumb and forefinger. In an overhand method, due to the extended width of the extended charging handle 124 relative to the receiver 102, users may be able to grasp the extended charging handle 124 from the top like a traditional slide using an overhand grip.

[0031] This versatile design may address a common complaint with internal bolt pistols, which may have small and sharp rear serrations that can be difficult to manipulate. The extended charging handle 124 may provide improved leverage and multiple gripping options, enhancing the overall user experience and ease of operation. In some cases, the receiver 102 may have a polished surface. This polished surface, in combination with the wider extended charging handle 124, may help prevent a user's hand from inadvertently gripping the receiver 102 during charging operations. The positioning of the rearward sight 114 and its relationship to the extended charging handle 124 may be designed to avoid interference during charging operations while maintaining proper sight alignment.

[0032] Referring to FIG. 4, a cutaway view of the firearm 100 exposes internal components within the receiver 102. A hammer 126 may be positioned within the receiver 102 and may be configured to rotate about a hammer axis 132. The hammer axis 132 defines a rotational pivot point for the hammer 126 during operation. A hammer spring 128 may be arranged to provide rotational force to the hammer 126, enabling a striking action for firing. The hammer spring 128 may be positioned inside a rear tang of the grip 104. In some cases, the hammer spring 128 may be loaded in a direction opposite to conventional designs, which may allow for efficient use of space within the grip 104 while maintaining proper functionality of a firing mechanism.

[0033] The recoil post 116 may be positioned at a rear portion of the receiver 102. A recoil post retaining pin 130 may extend through the recoil post 116 to secure the recoil post 116 in position within the receiver 102. Hammer spring 128 is retained by recoil post, which defines the hammer spring axis 129. The recoil post 116 may have a beak shape with a spring loaded configuration. In some cases, a hook on the recoil post 116 may engage a shelf on the receiver 102 to hold the receiver 102 down relative to the grip 104. The recoil post 116 may rotate on a hole that is drilled in rather than molded in, allowing for tight position control of a dimension from the hole to the shelf.

[0034] The receiver 102 may be secured to the grip 104 via a self-tensioning method. The recoil post 116 may be designed to pull a rear of the receiver 102 down when assembled. In some cases, a tensioning effect may be increased while the firearm 100 is firing. When the firearm 100 fires, the bolt assembly 118 may move rearward and load the recoil post 116, which may pull the receiver 102 rearward and downward. This self-tensioning arrangement may contribute to accuracy of the firearm 100.

[0035] A recoil assembly may include a dowel pin that is over molded or pressed into the grip 104. The dowel pin may be an off-the-shelf component that transfers recoil load from the receiver 102 to the grip 104. This arrangement may cause recoil forces to dissipate through metal-to-metal contact, reducing loading on plastic components of the grip 104.

[0036] The hammer spring 128 may provide high leverage against the hammer 126 at a hammer down position. In some cases, a point of contact between the hammer 126 and the hammer spring 128 may change through rotation of the hammer 126, creating a nonlinear force relationship. When the hammer 126 is in the hammer down position against the bolt assembly 118, a force of the hammer 126 against the bolt assembly 118 may be high. This high force may provide a self-tensioning lock up force that increases a force to pull the bolt assembly 118 out of battery.

[0037] The hammer 126 may have wire EDM sear surfaces. Wire EDM refers to wire electrical discharge machining, a process that may produce precise surface geometries. The wire EDM sear surfaces may contribute to a short, crisp trigger break, which may enhance trigger performance compared to molded-in sear surfaces.

[0038] Referring to FIG. 5, the hammer 126 is shown in an uncocked position within the receiver 102. The hammer 126 may include a hammer tail 134 that extends rearward from a main body of the hammer 126. The hammer tail 134 may interact with the hammer spring 128, which may be configured as a torsion spring. The hammer spring 128 may be positioned inside a rear tang of the grip 104 and may be loaded in a direction opposite to conventional hammer spring designs. This reverse-loaded configuration may allow for efficient use of space within the grip 104 while maintaining proper functionality of the firing mechanism.

[0039] The hammer 126 may have a uniquely shaped configuration that causes the hammer 126 to strike a firing pin at a grazing angle rather than perpendicular to an axis of the firing pin. Although this grazing angle may be geometrically inefficient, the hammer spring 128 may provide extremely high force against the hammer 126 due to a nonlinear relationship between a position of the hammer spring 128 and a force applied to the hammer 126. As the hammer 126 rotates about the hammer axis 132, a point of contact between the hammer 126 and the hammer spring 128 may change, resulting in varying leverage throughout the rotation. When the hammer 126 is in the uncocked position against the bolt assembly 118, the force of the hammer 126 against the bolt assembly 118 may be high, which may compensate for the geometric inefficiency of the grazing strike angle.

[0040] The firing pin may have a tapered design with a chamfered tail end. The tapered configuration and chamfered tail end may minimize drag and prevent the firing pin from nosing up during a firing sequence. When the hammer 126 strikes the firing pin at the grazing angle, the firing pin may tend to tip up within a bore of the bolt assembly 118. The chamfered tail end may reduce contact between the firing pin and bearing surfaces within the bolt assembly 118, thereby reducing friction and improving ignition efficiency.

[0041] The firing pin may be designed to be barely longer than a bolt face surface of the bolt assembly 118. This configuration may cause the hammer 126 to stop in the firing pin rather than hitting the bolt assembly 118. The grazing blow from the hammer 126 may be converted into forward force on the firing pin because the hammer 126 cannot travel further downward once the hammer 126 contacts the firing pin. The firing pin may have a round cross-section that is brought to a chisel tip for striking rimfire primers. The chisel tip geometry may provide a contact area suitable for compressing primer material without shearing brass of a cartridge case.

[0042] In some cases, a barrel sleeve may have a cut out for clearance with the hammer 126. The cut out may allow proper movement of the hammer 126 during a firing cycle without interference from the barrel sleeve.

[0043] A recoil spring of the bolt assembly 118 may be installed at a first length when outside the firearm 100 and may enter a second length condition when installed within the receiver 102, with the second length being slightly more compressed than the first length. A recoil pin may move from being tangent to a first position to being tangent to a second position on the recoil post 116. Travel of the recoil pin may be approximately half a diameter of the recoil pin. For example, for a recoil pin having a diameter of approximately 0.078 inches, the travel may be approximately 39 thousandths of an inch.

[0044] Due to the high lock up force provided by the hammer spring 128 configuration, a mass of the bolt assembly 118 may be reduced with no observable effect on operation of the firearm 100. In some cases, the bolt assembly 118 may be machined down to approximately 40 percent less mass while maintaining proper function. The high force of the hammer 126 against the bolt assembly 118 in the uncocked position may reduce reliance on inertia of the bolt assembly 118 to prevent early opening during firing.

[0045] Referring to FIG. 6, a rearward perspective view of the firearm 100 shows the recoil post 116 visible through an aperture defined in an upper portion of the receiver 102. The aperture may be positioned between the rearward sight 114 and the extended charging handle 124, allowing for visual confirmation of the presence and proper installation of the recoil post 116. The visibility of the recoil post 116 through the aperture may facilitate maintenance and inspection of the recoil post 116 without requiring complete disassembly of the firearm 100. The aperture may be designed to expose a portion of the recoil post 116 while balancing visibility with protection of internal components.

[0046] The receiver 102 may include a hammer track cut through a ceiling of the receiver 102. The hammer track may define a path through which the hammer 126 swings during operation of the firearm 100. The hammer track may be positioned to accommodate the hammer configuration and hammer spring arrangement described above, where the hammer 126 rotates through the hammer track to strike the firing pin.

[0047] The receiver 102 may be configured as a universal receiver for both 22 LR and Magnum versions of the firearm 100. A pocket may be defined on a top of the receiver 102 for an interrupter lug on a Magnum version of the firearm 100. On an LR version of the firearm 100, the pocket may be present but may not perform a function. This universal receiver design may allow the same receiver 102 to be used for both LR and Magnum configurations, reducing manufacturing complexity.

[0048] The receiver 102 may include an off-center recoil mechanism to accommodate a locking lug in a middle portion of the receiver 102 for the Magnum version. In some cases, the off-center recoil mechanism may be positioned to one side of a longitudinal axis of the receiver 102, leaving space in the middle for the locking lug to engage with a locking surface machined into the receiver 102. This arrangement may differ from other firearm designs where a recoil mechanism is positioned along a center axis of the receiver.

[0049] Referring to FIG. 7, a cutaway view of the firearm 100 shows the trigger 106 and a trigger return spring 136 within the receiver 102. The trigger 106 may be a flat-faced trigger that is 90 degrees at a point of break. This flat-faced configuration may provide a consistent and predictable trigger pull for improved shooting performance.

[0050] The trigger return spring 136 may be mounted above the trigger 106 and may interface with the trigger 106 to provide return force. The trigger return spring 136 may be a single spring that serves dual purposes, providing return force for both the trigger 106 and a trigger safety. This dual-purpose configuration may reduce a number of components within the firearm 100 while maintaining proper functionality of both the trigger 106 and the trigger safety.

[0051] A trigger pull weight of the firearm 100 may be adjustable by changing the trigger return spring 136. The trigger return spring 136 may be available in different strengths, allowing adjustment of the trigger pull weight between 3 pounds and higher weights. Different trigger return springs 136 with varying spring rates may be used to achieve different trigger pull weights, allowing for customization based on user preference or specific shooting applications.

[0052] To change the trigger return spring 136, a user may first remove an upper assembly of the firearm 100. With the trigger 106 and the trigger return spring 136 exposed, the user may push down on top coils of the trigger return spring 136 until the trigger return spring 136 disengages from a downward tooth of a trigger bar. The trigger return spring 136 may then be rocked slightly backward until the trigger return spring 136 can elongate behind the tooth. To insert a new trigger return spring 136, the process may be reversed, pushing the new trigger return spring 136 into a pocket at a slight angle, compressing the new trigger return spring 136 downward under the tooth, and then allowing the new trigger return spring 136 to elongate upward to be retained by the tooth.

[0053] Referring to FIG. 8, a perspective view of the bolt assembly 118 shows internal components and features. The bolt assembly 118 may include a bolt face 138 positioned at a forward end of the bolt assembly 118. An ejector 140 and a firing pin 142 may be integrated into the bolt face 138. The ejector 140 may be configured to eject spent cartridge casings from the firearm 100 after firing, while the firing pin 142 may be designed to strike a primer of a cartridge to initiate a firing sequence.

[0054] The extended charging handle 124 may be coupled to a rear portion of the bolt assembly 118. The extended charging handle 124 may allow a user to manually operate the bolt assembly 118, facilitating actions such as chambering a round or clearing a malfunction. On an LR version of the firearm 100, the extended charging handle 124 may be fixed to the bolt assembly 118 with two posts that go into counter bores. The extended charging handle 124 may snap into position via cam cuts in a back portion of the bolt assembly 118. When the extended charging handle 124 is installed, the extended charging handle 124 may go into position and snap into the counter bores, fixing the extended charging handle 124 to the bolt assembly 118.

[0055] The extended charging handle 124 may be configured as a one-piece snap-on ring design. This one-piece ring configuration may provide better purchase on the bolt assembly 118, which is an internal bolt design. Internal bolt pistols may have limited surfaces available for gripping because the bolt assembly 118 is positioned inside the receiver 102, allowing a user to grab only at a rear portion of the bolt assembly 118. The one-piece snap-on ring design of the extended charging handle 124 may address this limitation by providing an extended gripping surface that extends beyond a width of the receiver 102.

[0056] The bolt assembly 118 may incorporate a recoil assembly cross bar 144. The recoil assembly cross bar 144 may extend through the bolt assembly 118 perpendicular to a longitudinal axis of the bolt assembly 118. The recoil assembly cross bar 144 may serve as an anchor point for recoil springs or other components involved in cycling of the bolt assembly 118. A series of coil springs may be visible along a length of the bolt assembly 118. These springs may be housed within a main body of the bolt assembly 118 and may play a role in cycling and operation of the firearm 100. The springs may provide force to return the bolt assembly 118 to a forward position after firing. The components of the bolt assembly 118 may be arranged in a linear configuration, with the bolt face 138 positioned at a front, followed by an internal spring mechanism, with the extended charging handle 124 at a rear. This arrangement may facilitate smooth operation of the bolt assembly 118 within the receiver 102 of the firearm 100.

[0057] The firearm 100 may include a modular barrel system that allows for customization and barrel changes. A barrel may be removably coupled to the receiver 102, where the barrel and the receiver 102 utilize a locking system including an axial lug and a rotational key for repeatable barrel positioning. A set screw may be configured to bias the barrel against the receiver 102 to secure the barrel in a fixed position relative to the receiver 102.

[0058] The barrel may include a barrel core with a standard thread and a stanchion where an iron sight is mounted. Grooves may be positioned on either side of the barrel adjacent to the stanchion for barrel sleeve attachment. A barrel sleeve may be configured to slide onto the barrel from a chamber end of the barrel. The barrel sleeve may have detents at an end of slots that snap onto the stanchion of the barrel core. The barrel sleeve may be available in multiple profiles including round sleeves and square sleeves in different lengths such as seven inch and five inch configurations. The barrel sleeve may have a window on a top surface through which a caliber mark on the barrel shows. The caliber mark may be machined into the barrel rather than laser engraved, allowing the caliber mark to show through the barrel sleeve window regardless of which barrel sleeve profile is installed.

[0059] The receiver 102 may define an elliptical opening configured to receive the barrel. The elliptical opening may have a geometry that permits the barrel to be inserted in a first orientation and rotated to a second orientation in which the axial lug and the rotational key engage with corresponding features of the receiver 102. The barrel may have an elliptical cross-section at certain sections with round sections alternating with elliptical sections along a length of the barrel, creating interrupted sections for the locking interface. This interrupted geometry may allow the barrel to pass through the elliptical opening during insertion and then engage with locking features upon rotation.

[0060] The barrel may include a feed ramp, and the elliptical opening may be configured to permit the feed ramp to pass through the elliptical opening during insertion of the barrel into the receiver 102. When the barrel is positioned in the first orientation, the feed ramp may drop down through the elliptical opening. Once the feed ramp clears the elliptical opening, the barrel may be moved upward and forward to engage the locking features.

[0061] The axial lug may be positioned on the barrel and configured to engage with an axial pocket defined in the receiver 102 to constrain axial movement of the barrel relative to the receiver 102. The rotational key may be positioned on the barrel and configured to engage with a rotational pocket defined in the receiver 102 to constrain rotational movement of the barrel about a longitudinal axis of the barrel. The rotational key may be spaced apart from the axial lug along the longitudinal axis of the barrel.

[0062] The barrel may have vertical support through tangential contact from a barrel diameter to a top of the receiver 102 at two spaced locations. No vertical contact may be present in areas of the axial lug and the rotational key. The axial lug section may provide pure axial contact, while the rotational key section may provide pure roll contact. This arrangement may position vertical support points at extremities of the barrel engagement area, straddling the set screw location to provide stable barrel positioning.

[0063] A clearance between the rotational key and the rotational pocket may be approximately 2 thousandths of an inch on either side. This tight clearance may control barrel roll position, allowing the barrel to return to a consistent rotational position each time the barrel is installed. The tight rotational clearance may maintain point of impact and point of aim convergence when iron sights are split between the receiver 102 and the barrel.

[0064] A clearance between the axial lug and the axial pocket may be approximately 12 thousandths of an inch nominal. This clearance may allow the barrel to bias forward against a front of the axial pocket when the bolt assembly 118 pushes the barrel forward during operation. The forward bias arrangement may maintain consistent barrel position relative to the receiver 102 for proper feeding and headspacing.

[0065] The set screw may be positioned between the axial lug and the rotational key along the longitudinal axis of the barrel. This positioning may place the set screw in a balanced location relative to the vertical support points provided by the tangential contact areas. The set screw for barrel retention may use a same thread as an assembly screw that secures an upper assembly to the grip 104, allowing a same tool to be used for both fasteners during machining and assembly operations.

[0066] The barrel may include a flat surface configured to interface with the set screw. The flat surface may be oriented to resist rotation of the barrel when the set screw is tightened. The set screw may have a ring at a top of the set screw that bites into the flat surface on a barrel bottom to prevent loosening. The ring configuration may provide improved retention compared to a set screw bearing against a round surface, where the set screw would have two-point contact and may be more likely to loosen during operation.

[0067] Referring to FIG. 9, a magnum bolt assembly 218 may be configured for use with magnum rimfire cartridges in the firearm 100. The magnum bolt assembly 218 may include a delayed blowback system that provides positive case retention during firing of higher pressure cartridges such as .17 HMR and .22 WMR. The delayed blowback system may differ from straight blowback systems used in standard .22 LR firearms, where the bolt assembly 118 described above may operate without a locking mechanism.

[0068] The magnum bolt assembly 218 may include a magnum bolt body 219 that forms a main structural component of the magnum bolt assembly 218. A bolt face 238 may be positioned at a forward end of the magnum bolt body 219 and may be configured to interface with cartridges during operation. A push feed extractor 240 may be coupled to the magnum bolt body 219 and may be secured by an extractor pin 239. The push feed extractor 240 may increase an amount of support that a cartridge rim has during firing, minimizing a chance of blown cases with magnum rimfire ammunition. A firing pin 242 may extend through the magnum bolt body 219 and may be configured to strike a primer of a cartridge to initiate firing.

[0069] The delayed blowback system of the magnum bolt assembly 218 may include a locking block 250 and a carrier 252. The locking block 250 may be positioned within the magnum bolt body 219 and may be configured to engage a locking surface machined into the receiver 102 when the magnum bolt assembly 218 is in a locked position. The carrier 252 may interface with the locking block 250 through an angled ramp configuration. An angled interface between the locking block 250 and the carrier 252 may be configured to cause the locking block 250 to disengage from the locking surface when the carrier 252 moves rearward.

[0070] The magnum bolt assembly 218 may include a recoil guide rod 254 that extends rearward from the carrier 252 through the magnum bolt assembly 218. A recoil spring 258 may be disposed around the recoil guide rod 254 and may provide return force for cycling the magnum bolt assembly 218. A recoil spring stop nut 256 may be positioned at a rear portion of the recoil guide rod 254 to retain the recoil spring 258 in position. A recoil pin e-clip 264 may secure components of a recoil assembly within the magnum bolt assembly 218. A plurality of coil pins 266 may be used throughout the magnum bolt assembly 218 to secure various components in their respective positions.

[0071] An extended charging handle 224 may be coupled to a rear portion of the magnum bolt assembly 218. The extended charging handle 224 may be connected to the carrier 252 via a charge handle link 260. A charging handle retaining clip 262 may secure the extended charging handle 224 to the magnum bolt body 219. The charge handle link 260 may include a leg that is inserted into a hole on the extended charging handle 224, connecting the extended charging handle 224 to the carrier 252.

[0072] The magnum bolt assembly 218 may include an extra rod that goes through the magnum bolt body 219, where the extended charging handle 224 pulls back slightly to pull the rod rearward, which pulls the carrier 252 back to disengage the locking block 250 from the locking surface. Rearward movement of the extended charging handle 224 may cause the carrier 252 to move rearward and disengage the locking block 250 from the locking surface. This linkage arrangement may convert the rifle-style delayed blowback system into an internal bolt pistol configuration where the extended charging handle 224 is positioned at a rear of the magnum bolt assembly 218 rather than adjacent to the locking block 250.

[0073] The receiver 102 may include an off-center recoil mechanism to accommodate the locking block 250 in a middle portion of the receiver 102. On firearms with a center-mounted recoil mechanism, such as some existing rimfire pistol designs, the locking block 250 cannot be positioned in the middle of the receiver 102 because the recoil mechanism occupies that space. The off-center recoil mechanism of the firearm 100 may leave space in the middle of the receiver 102 for the locking block 250 to engage with the locking surface. A pocket may be defined on a top of the receiver 102 for an interrupter lug on the magnum version of the firearm 100, which may correspond to a location where the locking block 250 engages the receiver 102.

[0074] Referring to FIG. 10, an exploded perspective view of the magnum bolt assembly 218 shows the spatial arrangement of components that form the delayed blowback system. At a forward end of the magnum bolt assembly 218, the bolt face 238 may be positioned to interface with cartridges during operation. The push feed extractor 240 may be coupled to the bolt face 238 via the extractor pin 239. An extractor spring 241 may be positioned to provide biasing force for the push feed extractor 240, urging the push feed extractor 240 toward a cartridge extraction position. The firing pin 242 may extend through the magnum bolt body 219 and may be configured to strike a primer of a cartridge to initiate firing.

[0075] The magnum bolt body 219 may form a main structural component of the magnum bolt assembly 218 and may house internal mechanisms of the delayed blowback system. The locking block 250 may be positioned within the magnum bolt body 219 and may interface with the carrier 252. The locking block 250 and the carrier 252 may work together to provide delayed blowback action, with the locking block 250 engaging a locking surface in the receiver 102 when the magnum bolt assembly 218 is in battery.

[0076] The recoil guide rod 254 may extend rearward from the carrier 252 and may pass through the recoil spring 258. The recoil spring 258 may be disposed around the recoil guide rod 254 along a length of the recoil guide rod 254. The carrier 252 may be connected to the recoil guide rod 254 such that rearward movement of the carrier 252 compresses the recoil spring 258. The recoil guide rod 254 may extend through the magnum bolt assembly 218 along a longitudinal axis of the magnum bolt assembly 218. The recoil spring stop nut 256 may be positioned at a rear of the recoil guide rod 254 to retain the recoil spring 258 in place and prevent the recoil spring 258 from sliding off the recoil guide rod 254. The recoil pin e-clip 264 may secure components of a recoil assembly within the magnum bolt assembly 218.

[0077] The charge handle link 260 may connect the carrier 252 to the extended charging handle 224 positioned at a rear of the magnum bolt assembly 218. The extended charging handle 224 may allow manual operation of the magnum bolt assembly 218 and, through the charge handle link 260, may enable disengagement of the locking block 250 when the extended charging handle 224 is pulled rearward. The coil pins 266 may be used to secure various components within the magnum bolt assembly 218, maintaining proper alignment and retention of internal parts during operation.

[0078] Referring to FIG. 11, a perspective view of the magnum bolt assembly 218 shows internal components and features of the delayed blowback system. The magnum bolt assembly 218 may include the magnum bolt body 219 that forms a main structural element of the magnum bolt assembly 218. At a forward end of the magnum bolt assembly 218, the bolt face 238 may be positioned to interface with cartridges during operation. The push feed extractor 240 may be integrated into a bolt face area and may be secured by the extractor pin 239. The firing pin 242 may extend through the magnum bolt body 219 and may be visible at the bolt face 238.

[0079] The magnum bolt assembly 218 may incorporate the delayed blowback system including the locking block 250 and the carrier 252. The locking block 250 may be positioned within the magnum bolt body 219 and may be configured to engage a locking surface machined into the receiver 102 when the magnum bolt assembly 218 is in a locked position. The carrier 252 may interface with the locking block 250 through an angled ramp configuration. An angled interface between the locking block 250 and the carrier 252 may be configured to cause the locking block 250 to disengage from the locking surface when the carrier 252 moves rearward.

[0080] The recoil guide rod 254 may extend rearward from the carrier 252 and may support the recoil spring 258. The recoil spring 258 may be positioned along the recoil guide rod 254 and may provide return force for cycling the magnum bolt assembly 218. The recoil pin e-clip 264 may be visible and may serve to retain components of a recoil assembly within the magnum bolt assembly 218.

[0081] When the firearm 100 is fired, the locking block 250 may be pushed back against the locking surface of the receiver 102. The angled interface between the locking block 250 and the carrier 252 may push the locking block 250 downward as the locking block 250 is driven rearward. This downward movement of the locking block 250 may in turn push downward and backward on an angled ramp of the carrier 252, compressing the recoil spring 258. Upon the locking block 250 clearing the locking surface of the receiver 102, remaining energy from a fired round may push the magnum bolt body 219 rearward to complete a firing cycle.

[0082] Rearward movement of the extended charging handle 224 may cause the carrier 252 to move rearward and disengage the locking block 250 from the locking surface. When a user pulls rearward on the extended charging handle 224, the charge handle link 260 may transmit this motion to the carrier 252. As the carrier 252 moves rearward, the angled interface between the carrier 252 and the locking block 250 may allow the locking block 250 to move downward out of engagement with the locking surface, thereby unlocking the magnum bolt assembly 218 and permitting the magnum bolt body 219 to travel rearward for manual cycling operations.

[0083] Referring to FIG. 12, a cross-sectional view of a portion of the magnum bolt assembly 218 shows an arrangement of components that provide cartridge extraction and support functionality. The magnum bolt assembly 218 may include the magnum bolt body 219 that houses several components of the delayed blowback system. The bolt face 238 may be visible at a forward portion of the magnum bolt body 219 and may define a surface against which a cartridge head rests during firing.

[0084] The magnum bolt assembly 218 may further include a push feed extractor 240 configured to provide cartridge support during firing. The push feed extractor 240 may be positioned within the magnum bolt body 219 adjacent to the bolt face 238. The push feed extractor 240 may be biased by an extractor spring 241 and secured to the magnum bolt body 219 by an extractor pin. The extractor spring 241 may be arranged to urge the push feed extractor 240 toward a cartridge engagement position, where the push feed extractor 240 may grip a rim of a cartridge case for extraction after firing.

[0085] The push feed extractor 240 may differ from controlled round feed systems used in other rimfire handguns. In a controlled round feed system, an extractor may grip a cartridge rim as the cartridge is stripped from a magazine and may maintain grip throughout a feeding and firing cycle. In contrast, the push feed extractor 240 may allow a cartridge to be pushed into a chamber without the push feed extractor 240 initially gripping the cartridge rim. The push feed extractor 240 may then snap over the cartridge rim once the cartridge is fully chambered. This push feed configuration may increase an amount of support that the cartridge rim has during firing, which may minimize a chance of blown cases when firing magnum rimfire ammunition such as .17 HMR or .22 WMR cartridges.

[0086] The locking block 250 may be shown in an engaged position within the magnum bolt body 219. The spatial relationship between the push feed extractor 240, the extractor spring 241, and the locking block 250 within the magnum bolt body 219 may demonstrate how these components are arranged to provide both delayed blowback functionality and improved cartridge support. The push feed extractor 240 and extractor spring 241 may work together to provide cartridge extraction functionality while the locking block 250 interfaces with a locking surface of the receiver 102 to delay opening of the magnum bolt assembly 218 until chamber pressure has dropped to a safe level. This combination of push feed extraction and delayed blowback operation may provide reliable function with higher pressure magnum rimfire cartridges.

[0087] Referring to FIGS. 13A-13B, side cross-sectional views of the magnum bolt assembly 218 show the locking block 250 in locked and unlocked positions, respectively. In FIG. 13A, the locking block 250 may be shown in a locked position where the locking block 250 engages with a locking surface of the receiver 102. The carrier 252 may be positioned beneath the locking block 250 and may interface with the recoil guide rod 254, which extends rearward through the magnum bolt assembly 218. The charge handle link 260 may connect the carrier 252 to the extended charging handle 224, enabling manual operation of the magnum bolt assembly 218.

[0088] In FIG. 13B, the magnum bolt assembly 218 may be shown with the locking block 250 in an unlocked position. An arrow indicating displacement of locking block 251 may show a downward movement of the locking block 250 as the locking block 250 disengages from the locking surface of the receiver 102. An arrow indicating displacement of charging handle 225 may indicate a rearward movement of the extended charging handle 224 during an unlocking operation. When the extended charging handle 224 is pulled rearward, the charge handle link 260 may pull the carrier 252 rearward, which may in turn cause the locking block 250 to move downward along an angled ramp interface with the carrier 252, thereby disengaging the locking block 250 and allowing the magnum bolt body 219 to travel rearward.

[0089] The extended charging handle 224 may be coupled to the magnum bolt body 219 via a sliding connection that permits limited rearward movement of the extended charging handle 224 relative to the magnum bolt body 219. The sliding connection may include bosses on the extended charging handle 224 that interface with slots defined in the magnum bolt body 219. The bosses may be round protrusions that extend from the extended charging handle 224 and may be received within elongated slots formed in the magnum bolt body 219. This sliding connection may allow the extended charging handle 224 to travel rearward a limited distance relative to the magnum bolt body 219 before the magnum bolt body 219 begins to move rearward.

[0090] When a user pulls rearward on the extended charging handle 224, the extended charging handle 224 may first move rearward within the slots of the magnum bolt body 219 as indicated by the arrow indicating displacement of charging handle 225. This initial rearward movement of the extended charging handle 224 may be transmitted through the charge handle link 260 to the carrier 252. As the carrier 252 moves rearward, the angled interface between the carrier 252 and the locking block 250 may cause the locking block 250 to move downward as indicated by the arrow indicating displacement of locking block 251. Once the locking block 250 clears the locking surface of the receiver 102, continued rearward force on the extended charging handle 224 may cause the magnum bolt body 219 to travel rearward along with the extended charging handle 224 for manual cycling of the magnum bolt assembly 218.

[0091] The arrangement of the locking block 250 and the carrier 252 may provide a delayed blowback system where the angled interface between these components controls timing of bolt unlocking during a firing cycle. This configuration may allow the extended charging handle 224, positioned at a rear of the magnum bolt assembly 218, to actuate a locking mechanism located at a front of the magnum bolt assembly 218 through a mechanical linkage provided by the charge handle link 260 and the carrier 252. The sliding connection between the extended charging handle 224 and the magnum bolt body 219 may provide the initial travel distance for the extended charging handle 224 to disengage the locking block 250 before the magnum bolt body 219 begins rearward travel.

[0092] Referring to FIGS. 14A-14B, isolated views of the locking block 250 and the carrier 252 show the mechanical interaction between these two components in locked and unlocked positions. The isolated views may illustrate the relationship between the locking block 250 and the carrier 252 without surrounding components of the magnum bolt assembly 218, providing a clear depiction of the interface geometry that controls locking and unlocking operations.

[0093] An arrow indicating displacement of locking block 251 may show a direction of movement of the locking block 250 as the locking block 250 transitions between locked and unlocked states. An arrow indicating displacement of charging handle 225 may indicate a corresponding movement direction associated with charging handle operation. The locking block 250 may interface with an angled ramp surface on the carrier 252. When the locking block 250 is pushed rearward against a locking surface of the receiver 102, the angled interface may cause the locking block 250 to move downward as indicated by the arrow indicating displacement of locking block 251.

[0094] The downward movement of the locking block 250 may in turn push downward and backward on the angled ramp of the carrier 252. The relationship between the locking block 250 and the carrier 252 may demonstrate a delayed blowback mechanism where the locking block 250 clears the locking surface before a bolt body can travel rearward. The arrows indicating displacement of locking block 251 and displacement of charging handle 225 may illustrate coordinated movement of these components during an unlocking sequence, showing how manual operation of a charging handle results in disengagement of the locking block 250 from a locked position.

[0095] The angled interface between the locking block 250 and the carrier 252 may convert rearward motion of the carrier 252 into downward motion of the locking block 250. This cam-like action may allow the locking block 250 to be driven out of engagement with the locking surface of the receiver 102 through rearward force applied to the carrier 252. The geometry of the angled ramp may determine a mechanical advantage and timing relationship between carrier movement and locking block disengagement. The isolated views may show that the locking block 250 and the carrier 252 form a self-contained locking mechanism that responds to rearward force on the carrier 252 by releasing the locking block 250 from engagement with the receiver 102.

[0096] Referring to FIG. 15A, a magazine 300 may be configured for use with the firearm 100. The magazine 300 may include an injection molded magazine body 302 configured to retain rimfire cartridges in an angled orientation. The injection molded magazine body 302 may form a primary structure for retaining cartridges within the magazine 300. A follower 304 may be positioned within the injection molded magazine body 302 and may be configured to support and feed cartridges upward during operation. The follower 304 may be configured to pivot to support the angled rimfire cartridges, allowing the follower 304 to accommodate the natural tendency of rimfire cartridges to angle themselves due to a rim of the cartridges being wider than a rest of a cartridge body.

[0097] A stamped backer plate 310 may be attached to the injection molded magazine body 302. The stamped backer plate 310 may be positioned at a rear portion of the injection molded magazine body 302 and may provide a wear-resistant surface. The stamped backer plate 310 may include a plurality of round holes along sides of the stamped backer plate 310 that interface with corresponding round posts on the injection molded magazine body 302 to secure the stamped backer plate 310 in position. A base plate 306 may be positioned at a bottom of the magazine 300. The base plate 306 may feature a textured surface with a plurality of raised elements to facilitate grip during magazine insertion and removal.

[0098] The magazine 300 may be built around a 1911 size footprint to accommodate longer magnum cartridges while using a common magazine footprint. A maximum length of .22 WMR and .17 HMR cartridges may be 1.350 inches and 1.365 inches respectively, which may be longer than a maximum cartridge length of .45 ACP at 1.275 inches that a 1911 magazine was designed around. The angled cartridge orientation within the injection molded magazine body 302 may accommodate the longer cartridge length while maintaining the 1911 magazine footprint. The magazine 300 may be compatible with 1911 magazine holders and pouches, allowing users to utilize existing 1911 magazine carrying equipment with the firearm 100.

[0099] Referring to FIG. 15B, a perspective view of the magazine 300 shows the injection molded magazine body 302 with a cartridge positioned on the follower 304. The injection molded magazine body 302 may form a main housing structure for retaining cartridges within the magazine 300. The follower 304 may be positioned within the injection molded magazine body 302 and may be visible near a top portion of the magazine 300, where a cartridge can be seen resting on the follower 304. The follower 304 may be configured to move vertically within the injection molded magazine body 302 as cartridges are loaded and fed from the magazine 300.

[0100] The follower 304 may include protrusions extending from sides of the follower 304. The protrusions may be configured to interface with slots defined in the injection molded magazine body 302 to guide movement of the follower 304 during loading and unloading. The injection molded magazine body 302 may include elongated slots along sides of the injection molded magazine body 302 that receive the protrusions of the follower 304. As cartridges are loaded into the magazine 300, the follower 304 may move downward within the injection molded magazine body 302, with the protrusions traveling along the slots to maintain proper alignment of the follower 304. During feeding operations, the follower 304 may move upward to push cartridges toward feed lips of the magazine 300, with the protrusions sliding along the slots to guide the upward movement of the follower 304.

[0101] The stamped backer plate 310 may be attached to one side of the injection molded magazine body 302. The stamped backer plate 310 may feature a plurality of holes along sides of the stamped backer plate 310 that interface with corresponding posts on the injection molded magazine body 302 to secure the stamped backer plate 310 in position. The base plate 306 may be positioned at a bottom of the magazine 300 and may serve to close a lower end of the injection molded magazine body 302 while retaining internal components such as a follower spring within the magazine 300.

[0102] Referring to FIG. 15C, a cross-sectional view of the magazine 300 shows internal components and their arrangement within the injection molded magazine body 302. The injection molded magazine body 302 may form an outer structure of the magazine 300 and may be configured to retain cartridges in an angled orientation. The angled orientation may take advantage of a natural tendency of rimfire cartridges to angle themselves due to a rim of the cartridges being wider than a rest of a cartridge body.

[0103] The stamped backer plate 310 may be attached to a rear of the injection molded magazine body 302. The stamped backer plate 310 may provide a thin, wear-resistant surface compared to a comparable injection molded plastic backer. The stamped backer plate 310 may interface with the injection molded magazine body 302 through a connection where flared sides of the injection molded magazine body 302 are compressed inward and a plurality of round posts interface with a plurality of round holes on sides of the stamped backer plate 310.

[0104] A follower spring 308 may be positioned within the injection molded magazine body 302. The follower spring 308 may provide upward force to bias cartridges toward a top of the magazine 300. A follower spring plunger 312 may be positioned at an upper end of the follower spring 308. The follower spring plunger 312 may interface with the follower 304 to support angled rounds of ammunition within the magazine 300. The base plate 306 may be positioned at a bottom of the magazine 300 and may serve to retain internal components within the injection molded magazine body 302.

[0105] The injection molded magazine body 302 may include internal lips positioned near the stamped backer plate 310. The internal lips may be configured to control positioning of rimfire cartridges to minimize rim-lock. Rim-lock may be an issue common with rimmed cartridges, both centerfire and rimfire, where a rim of one cartridge may become positioned behind a rim of an adjacent cartridge, preventing proper feeding. The internal lips may control positioning of rounds depending on how loaded or unloaded the magazine 300 is, helping to prevent the rims of adjacent cartridges from overlapping in a manner that would cause rim-lock during feeding operations.

[0106] Referring to FIG. 15D, an exploded view of the magazine 300 shows the spatial arrangement of components that form the magazine assembly. The injection molded magazine body 302 may form a main housing structure of the magazine 300 and may be configured to retain cartridges in a stacked arrangement. The injection molded magazine body 302 may feature viewing windows along a side of the injection molded magazine body 302 that allow visual confirmation of an ammunition level within the magazine 300.

[0107] The injection molded magazine body 302 may include a plurality of raised posts positioned along sides of the injection molded magazine body 302. The plurality of raised posts may be round protrusions that extend outward from exterior surfaces of the injection molded magazine body 302. The stamped backer plate 310 may include a plurality of holes configured to interface with the plurality of raised posts to secure the stamped backer plate 310 to the injection molded magazine body 302. The plurality of holes may be round apertures formed in the stamped backer plate 310 that correspond in position and size to the plurality of raised posts on the injection molded magazine body 302.

[0108] The injection molded magazine body 302 may include sides configured to flair outward. The outward flair of the sides may be an intentional design feature of the injection molded magazine body 302 that facilitates assembly with the stamped backer plate 310. When the stamped backer plate 310 is installed onto the injection molded magazine body 302, installation of the stamped backer plate 310 may compress the sides inward to engage the plurality of raised posts with the plurality of holes. The compression of the flared sides inward may cause the plurality of raised posts to align with and enter the plurality of holes in the stamped backer plate 310, thereby locking the stamped backer plate 310 and the injection molded magazine body 302 together.

[0109] The follower 304 may be positioned within the injection molded magazine body 302 and may be configured to move vertically within the injection molded magazine body 302 to push cartridges upward toward feed lips during operation. The follower 304 may include protrusions on sides of the follower 304 that interface with slots along sides of the injection molded magazine body 302, providing guidance as the follower 304 moves through a range of motion during loading and unloading. The base plate 306 may be positioned at a bottom of the magazine 300 and may provide a foundation for the magazine assembly. The base plate 306 may feature a textured surface with a plurality of ridges that may assist with magazine removal from the firearm 100.

[0110] The firearm 100 may include an ambidextrous safety system configured to provide user-selectable safe and fire modes from either side of the firearm 100. The ambidextrous safety system may include a strong side safety lever and a weak side safety lever that are mechanically linked to rotate together. The strong side safety lever may include a shaft that extends through the grip 104 from one side to an opposite side. The weak side safety lever may attach to the shaft via a screw and a keyway shape connection. The keyway shape connection may provide rotational coupling between the weak side safety lever and the shaft such that rotation of either safety lever causes corresponding rotation of the other safety lever.

[0111] The grip 104 may include molded pockets configured to house detent components for the ambidextrous safety system. A first molded pocket may be configured to receive a spring and a ball bearing that form a detent mechanism. The detent mechanism may provide positive tactile feedback when the safety is moved between safe and fire positions. The detent mechanism may include an eighth inch diameter spring positioned within a hole having a diameter of approximately 130 thousandths of an inch. An eighth inch diameter ball bearing may be positioned above the spring within the hole. The spring may bias the ball bearing outward against a surface of the safety lever, and the ball bearing may engage detent features on the safety lever to provide distinct click positions corresponding to safe and fire modes.

[0112] The grip 104 may include an anti-rotational stop that interfaces with the safety lever to define rotational limits of the safety. The anti-rotational stop may be tapered down at an angle. The tapered configuration of the anti-rotational stop may position a top stop surface at a location that defines a maximum rotational position of the safety lever. When the safety lever rotates to the fire position, the safety lever may bottom out against the anti-rotational stop. The anti-rotational stop may be positioned far from a rotational axis of the safety lever, providing stable rotational constraint.

[0113] The ambidextrous safety system may include safety paddles that are configured to be shallow in profile. Each safety paddle may have a thickness of approximately 50 thousandths of an inch. The shallow profile of the safety paddles may allow the safety paddles to sit within pockets formed in the grip 104 adjacent to sweep cuts. The sweep cuts may be contoured surfaces on the grip 104 that allow a user's knuckle to rest against the grip 104 while operating the safety. When a user thumbs the safety paddle downward to move from safe to fire mode, the user's knuckle may rest in the sweep cut while the safety paddle moves within the adjacent pocket. The shallow safety paddle may move inside the user's hand without causing interference or discomfort during operation. Clause 21. A firearm comprising: a receiver; a grip extending from the receiver; a barrel coupled to the receiver; a bolt assembly housed within the receiver; and an extended charging handle coupled to the bolt assembly, wherein the extended charging handle has a width greater than a width of the receiver.

[0114] The ambidextrous safety system may include fire indicator elements that provide visual indication of the fire mode. Each fire indicator may be a red ball having a diameter of approximately 157 thousandths of an inch. The red ball may be positioned within a hole in the grip 104 in an interference fit configuration. When the safety is in the fire position, the red ball may be visible to indicate that the firearm 100 is ready to fire. When the safety is moved to the safe position, the safety paddle may rotate to cover the red ball, obscuring the fire indicator from view. The covering of the red ball by the safety paddle may provide both visual confirmation of the safe mode and protection of the fire indicator element.

[0115] The detent mechanism may produce a distinct click sensation when the safety is moved between positions. As the safety lever rotates from the safe position toward the fire position, the ball bearing may ride along a surface of the safety lever until the ball bearing engages a detent feature corresponding to the fire position. The spring-loaded ball bearing may snap into the detent feature, producing tactile and audible feedback that confirms the safety has reached the fire position. Similarly, when the safety lever is rotated from the fire position toward the safe position, the ball bearing may disengage from the fire position detent feature and engage a detent feature corresponding to the safe position, again producing tactile and audible feedback. The metal-to-metal contact between the ball bearing and the safety lever surfaces may provide consistent and positive detent action.

[0116] The following clauses illustrated example subject matter described herein.

[0117] Clause 1. A firearm comprising: a receiver; a barrel removably coupled to the receiver, wherein the barrel and the receiver utilize a locking system comprising an axial lug and a rotational key for repeatable barrel positioning; a bolt assembly housed within the receiver; and a set screw configured to bias the barrel against the receiver to secure the barrel in a fixed position relative to the receiver.

[0118] Clause 2. The firearm of clause 1, wherein the axial lug is positioned on the barrel and configured to engage with an axial pocket defined in the receiver to constrain axial movement of the barrel relative to the receiver.

[0119] Clause 3. The firearm of clause 2, wherein the rotational key is positioned on the barrel and configured to engage with a rotational pocket defined in the receiver to constrain rotational movement of the barrel about a longitudinal axis of the barrel.

[0120] Clause 4. The firearm of clause 3, wherein the rotational key is spaced apart from the axial lug along the longitudinal axis of the barrel.

[0121] Clause 5. The firearm of clause 4, wherein the set screw is positioned between the axial lug and the rotational key along the longitudinal axis of the barrel.

[0122] Clause 6. The firearm of clause 1, wherein the barrel includes a flat surface configured to interface with the set screw, the flat surface being oriented to resist rotation of the barrel when the set screw is tightened.

[0123] Clause 7. The firearm of clause 1, wherein the receiver defines an elliptical opening configured to receive the barrel, the elliptical opening having a geometry that permits the barrel to be inserted in a first orientation and rotated to a second orientation in which the axial lug and the rotational key engage with corresponding features of the receiver.

[0124] Clause 8. The firearm of clause 7, wherein the barrel includes a feed ramp, and wherein the elliptical opening is configured to permit the feed ramp to pass through the elliptical opening during insertion of the barrel into the receiver.

[0125] Clause 9. The firearm of clause 1, further comprising a barrel sleeve configured to slide onto the barrel from a chamber end of the barrel.

[0126] Clause 10. A firearm comprising: a receiver; a grip extending from the receiver; a barrel coupled to the receiver; a bolt assembly housed within the receiver, the bolt assembly comprising a locking block and a carrier, wherein the locking block is configured to engage a locking surface of the receiver when the bolt assembly is in a locked position, and wherein an angled interface between the locking block and the carrier is configured to cause the locking block to disengage from the locking surface when the carrier moves rearward; and a charging handle coupled to the bolt assembly and connected to the carrier via a charge handle link, wherein rearward movement of the charging handle causes the carrier to move rearward and disengage the locking block from the locking surface.

[0127] Clause 11. The firearm of clause 10, wherein the charging handle is coupled to a bolt body of the bolt assembly via a sliding connection that permits limited rearward movement of the charging handle relative to the bolt body.

[0128] Clause 12. The firearm of clause 11, wherein the sliding connection comprises bosses on the charging handle that interface with slots defined in the bolt body.

[0129] Clause 13. The firearm of clause 10, further comprising a recoil spring disposed around a recoil guide rod, wherein the carrier is connected to the recoil guide rod such that rearward movement of the carrier compresses the recoil spring.

[0130] Clause 14. The firearm of clause 13, wherein the recoil guide rod extends through the bolt assembly along a longitudinal axis of the bolt assembly.

[0131] Clause 15. The firearm of clause 10, wherein the bolt assembly further comprises a push feed extractor configured to provide cartridge support during firing.

[0132] Clause 16. The firearm of clause 15, wherein the push feed extractor is biased by an extractor spring and secured to a bolt body of the bolt assembly by an extractor pin.

[0133] Clause 17. A magazine for a firearm, the magazine comprising: an injection molded magazine body configured to retain rimfire cartridges in an angled orientation; a stamped backer plate attached to the injection molded magazine body, wherein the injection molded magazine body comprises a plurality of raised posts and the stamped backer plate comprises a plurality of holes configured to interface with the plurality of raised posts to secure the stamped backer plate to the injection molded magazine body; and a follower positioned within the injection molded magazine body, the follower configured to pivot to support the angled rimfire cartridges.

[0134] Clause 18. The magazine of clause 17, wherein the injection molded magazine body comprises sides configured to flair outward, and wherein installation of the stamped backer plate compresses the sides inward to engage the plurality of raised posts with the plurality of holes.

[0135] Clause 19. The magazine of clause 17, wherein the follower comprises protrusions extending from sides of the follower, the protrusions configured to interface with slots defined in the injection molded magazine body to guide movement of the follower during loading and unloading.

[0136] Clause 20. The magazine of clause 19, wherein the injection molded magazine body comprises internal lips positioned near the stamped backer plate, the internal lips configured to control positioning of the rimfire cartridges to minimize rim-lock.

[0137] Clause 21. A firearm comprising: a receiver; a grip extending from the receiver; a barrel coupled to the receiver; a bolt assembly housed within the receiver; and an extended charging handle coupled to the bolt assembly. wherein the extended charging handle has a width greater than a width of the receiver.

[0138] Clause 22. The firearm of clause 21, wherein the extended charging handle comprises textured surfaces for enhanced grip.

[0139] Clause 23. The firearm of clause 21, wherein the barrel is removably coupled to the receiver via a set screw.

[0140] Clause 24. The firearm of clause 23, further comprising a barrel sleeve that slides onto the barrel from a chamber end of the barrel.

[0141] Clause 25. The firearm of clause 21, further comprising a hammer positioned within the receiver and a hammer spring arranged to provide rotational force to the hammer.

[0142] Clause 26. The firearm of clause 25, wherein the hammer comprises a hammer tail that extends rearward from a main body of the hammer.

[0143] Clause 27. The firearm of any one of clauses 21 through 26, further comprising a recoil post positioned at a rear portion of the receiver, wherein the recoil post is visible through an aperture defined in the receiver.

[0144] Clause 28. A firearm comprising: a receiver; a grip extending from the receiver; a barrel removably coupled to the receiver; a bolt assembly housed within the receiver; a hammer positioned within the receiver; and a hammer spring arranged to provide rotational force to the hammer, wherein the hammer spring is positioned inside a rear tang of the grip.

[0145] Clause 29. The firearm of clause 28, wherein the hammer comprises a hammer tail that extends rearward from a main body of the hammer.

[0146] Clause 30. The firearm of clause 29, wherein the hammer spring is a torsion spring arranged to interact with the hammer tail.

[0147] Clause 31. The firearm of clause 28, wherein the barrel is removably coupled to the receiver via a set screw.

[0148] Clause 32. The firearm of clause 31, further comprising a barrel sleeve that slides onto the barrel from a chamber end of the barrel.

[0149] Clause 33. The firearm of clause 32, wherein the barrel and receiver utilize a locking system comprising an axial lug and a rotational key for repeatable barrel positioning.

[0150] Clause 34. The firearm of any one of clauses 28 through 33, further comprising an extended charging handle coupled to the bolt assembly, wherein the extended charging handle has a width greater than a width of the receiver and comprises textured surfaces for enhanced grip.

[0151] Clause 35. A method of operating a firearm, the method comprising: grasping an extended charging handle coupled to a bolt assembly of the firearm, wherein the extended charging handle has a width greater than a width of a receiver of the firearm; and manipulating the extended charging handle to cycle the bolt assembly.

[0152] Clause 36. The method of clause 35, wherein grasping the extended charging handle comprises gripping textured surfaces on the extended charging handle.

[0153] Clause 37. The method of clause 35, wherein manipulating the extended charging handle comprises using one of a slingshot grip, a pinch grip, or an overhand grip.

[0154] Clause 38. The method of clause 35, further comprising: removing a barrel from the firearm by loosening a set screw; and replacing the removed barrel with a different barrel.

[0155] Clause 39. The method of clause 38, further comprising sliding a barrel sleeve onto the different barrel from a chamber end of the different barrel.

[0156] Clause 40. The method of any one of clauses 35 through 39, further comprising adjusting a trigger pull weight of the firearm by changing a trigger spring.

[0157] While the disclosure has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore, it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the disclosure, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,”“an,”“at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and / or “a portion” is used the item may include a portion and / or the entire item unless specifically stated to the contrary.

Examples

Embodiment Construction

[0023] For purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the disclosure is intended by the illustration and description of certain embodiments of the disclosure. In addition, any alterations and / or modifications of the illustrated and / or described embodiment(s) are contemplated as being within the scope of the present disclosure. Further, any other applications of the principles of the disclosure, as illustrated and / or described herein, as would normally occur to one skilled in the art to which the disclosure pertains, are contemplated as being within the scope of the present disclosure.

[0024]Referring to FIG. 1, a firearm 100 may include a receiver 102 that forms a main body of the firearm 100. The receiver 102 may be constructed from case hardened steel,...

Claims

1. A firearm comprising:a receiver;a barrel removably coupled to the receiver, wherein the barrel and the receiver utilize a locking system comprising an axial lug and a rotational key for repeatable barrel positioning;a bolt assembly housed within the receiver; anda set screw configured to bias the barrel against the receiver to secure the barrel in a fixed position relative to the receiver.

2. The firearm of claim 1, wherein the axial lug is positioned on the barrel and configured to engage with an axial pocket defined in the receiver to constrain axial movement of the barrel relative to the receiver.

3. The firearm of claim 2, wherein the rotational key is positioned on the barrel and configured to engage with a rotational pocket defined in the receiver to constrain rotational movement of the barrel about a longitudinal axis of the barrel.

4. The firearm of claim 3, wherein the rotational key is spaced apart from the axial lug along the longitudinal axis of the barrel.

5. The firearm of claim 4, wherein the set screw is positioned between the axial lug and the rotational key along the longitudinal axis of the barrel.

6. The firearm of claim 1, wherein the barrel includes a flat surface configured to interface with the set screw, the flat surface being oriented to resist rotation of the barrel when the set screw is tightened.

7. The firearm of claim 1, wherein the receiver defines an elliptical opening configured to receive the barrel, the elliptical opening having a geometry that permits the barrel to be inserted in a first orientation and rotated to a second orientation in which the axial lug and the rotational key engage with corresponding features of the receiver.

8. The firearm of claim 7, wherein the barrel includes a feed ramp, and wherein the elliptical opening is configured to permit the feed ramp to pass through the elliptical opening during insertion of the barrel into the receiver.

9. The firearm of claim 1, further comprising a barrel sleeve configured to slide onto the barrel from a chamber end of the barrel.

10. A firearm comprising:a receiver;a grip extending from the receiver;a barrel coupled to the receiver;a bolt assembly housed within the receiver, the bolt assembly comprising a locking block and a carrier, wherein the locking block is configured to engage a locking surface of the receiver when the bolt assembly is in a locked position, and wherein an angled interface between the locking block and the carrier is configured to cause the locking block to disengage from the locking surface when the carrier moves rearward; anda charging handle coupled to the bolt assembly and connected to the carrier via a charge handle link, wherein rearward movement of the charging handle causes the carrier to move rearward and disengage the locking block from the locking surface.

11. The firearm of claim 10, wherein the charging handle is coupled to a bolt body of the bolt assembly via a sliding connection that permits limited rearward movement of the charging handle relative to the bolt body.

12. The firearm of claim 11, wherein the sliding connection comprises bosses on the charging handle that interface with slots defined in the bolt body.

13. The firearm of claim 10, further comprising a recoil spring disposed around a recoil guide rod, wherein the carrier is connected to the recoil guide rod such that rearward movement of the carrier compresses the recoil spring.

14. The firearm of claim 13, wherein the recoil guide rod extends through the bolt assembly along a longitudinal axis of the bolt assembly.

15. The firearm of claim 10, wherein the bolt assembly further comprises a push feed extractor configured to provide cartridge support during firing.

16. The firearm of claim 15, wherein the push feed extractor is biased by an extractor spring and secured to a bolt body of the bolt assembly by an extractor pin.

17. A magazine for a firearm, the magazine comprising:an injection molded magazine body configured to retain rimfire cartridges in an angled orientation;a stamped backer plate attached to the injection molded magazine body, wherein the injection molded magazine body comprises a plurality of raised posts and the stamped backer plate comprises a plurality of holes configured to interface with the plurality of raised posts to secure the stamped backer plate to the injection molded magazine body; anda follower positioned within the injection molded magazine body, the follower configured to pivot to support the angled rimfire cartridges.

18. The magazine of claim 17, wherein the injection molded magazine body comprises sides configured to flair outward, and wherein installation of the stamped backer plate compresses the sides inward to engage the plurality of raised posts with the plurality of holes.

19. The magazine of claim 17, wherein the follower comprises protrusions extending from sides of the follower, the protrusions configured to interface with slots defined in the injection molded magazine body to guide movement of the follower during loading and unloading.

20. The magazine of claim 19, wherein the injection molded magazine body comprises internal lips positioned near the stamped backer plate, the internal lips configured to control positioning of the rimfire cartridges to minimize rim-lock.

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