Polymeric ammunition and method of making the polymeric ammunition

Abstract

The present disclosure provides a shotgun shell comprising a hull formed from an extruded crosslinked polyolefin, a head coupled to the hull, a primer disposed in the head, a propellant contained within the hull, a wad positioned within the hull above the propellant, and a projectile contained within the hull above the wad. The crosslinked polyolefin may be polyethylene, polypropylene, polybutylene, or combinations thereof, and can be crosslinked using radiation, peroxide, silane, or azo compounds. The wad may also be formed from a crosslinked polyolefin. Methods of making the shotgun shell and a sabot formed from a crosslinked polyolefin are also disclosed.

Description

Attorney Docket No.: 421.23644-WOPOLYMERIC AMMUNITION AND METHOD OF MAKING THE POLYMERIC AMMUNITION CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Application No. 63 / 779,060, titled DELIVERY OF PROJECTILES FROM A RIFLED BORE, filed March 27, 2025, the contents of which are expressly incorporated by reference herein.TECHNICAL FIELD

[0002] The present disclosure relates to ammunition, and more particularly to polymeric shotgun shells and components including hulls, wads, and sabots formed from crosslinked polymeric materials.BACKGROUND

[0003] There exists a need for affordable replacements for conventional shotgun ammunition that can increase performance and operational capabilities. Lightweight polymer-based ammunition must meet the reliability and performance standards of existing field ammunition and be interchangeable with ammunition in existing weaponry. Reliable ammunition manufacture requires uniformity (e.g., projectile seating, projectile, strength, etc.) from one load to the next in order to obtain consistent pressures within the ammunition during firing prior to separation to create uniformed ballistic performance. Plastic casings have been known for many years and have produced in commercial quantities. The industry continues to develop designs and technology that can improve ballistics, handling characteristics, and resistance to adverse physical and natural conditions the ammunition will be exposed to during its intended life cycle.

[0004] Shortcomings of the known ammunition and methods of producing plastic or substantially plastic ammunition can include the possibility of the projectile location volatility, projectile dislodgement, insufficient chamber pressure, lack of uniformity from round to round, and portions of the ammunition fracture upon firing causing the weapon to jam, be damaged, or a danger when subsequent rounds are fired or when the ammunition portions themselves become projectiles. To overcome the above shortcomings, improvements in design and performance of polymeric materials are needed.SUMMARY

[0005] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended toAttorney Docket No.: 421.23644-WOidentify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] This disclosure provides polymeric ammunition and a method of preparing polymeric ammunition. Specifically, the disclosure reports shotgun shells and shotgun shell components such as shotgun hulls, wads, and wadding and sabots, made from selected crosslinked polymers, including but not limited to only crosslinked polyolefins, which are cost effective, consistently reliable and perform well under a range of applications and conditions.

[0007] Suitable embodiments provided in this disclosure include, for example, a shotgun shell comprising an extruded crosslinked polyolefin hull. In some embodiments, the shotgun shell has a hull of a crosslinked polyolefin is polyethylene, propylene, butylene, or combinations thereof. A suitable polyolefin can be a high-density polyethylene. Crosslinking process can be done using radiation or using peroxide, silane, or azo compounds.

[0008] Other embodiments provided in this disclosure include, for example, a shotgun shell comprising a crosslinked polyolefin sabot. In some embodiments, the shotgun shell has a sabot of a crosslinked polyolefin is polyethylene, propylene, butylene, or combinations thereof. A suitable polyolefin can be a high-density polyethylene.

[0009] Still other embodiments in this disclosure include, for example, a shotgun shell comprising a crosslinked polyolefin wads. In some embodiments, the shotgun shell has a wad of a crosslinked polyolefin is polyethylene, propylene, butylene, or combinations thereof. A suitable polyolefin can be a high-density polyethylene.

[0010] In the embodiments listed above, crosslinking processing can be done using radiation or using peroxide, silane, or azo compounds. Further, the crosslinked polyolefin can be crosslinked during forming (e.g., by extrusion or injection molding) or crosslinked after forming.

[0011] Other embodiments are a shotgun shell comprising a base, a primer, a propellant, a wad, shot, and a hull, wherein one or more the shotgun shell components, such as a hull, sabot or wad comprise a crosslinked polyolefin. In some embodiments the hull comprises crosslinked high-density polyethylene. In other embodiments, the shotgun shell is free of a conventional pressure pusher plate.

[0012] This disclosure also includes, for example, a method of making the shotgun shell, wherein the method comprises forming a shotgun shell with components that are made from or with a crosslinked polyolefin. Some embodiments include the step of forming a hull, sabot or wad that comprises extruding or injection molding the crosslinked polyolefin to form oneAttorney Docket No.: 421.23644-WOor more of these components. In suitable embodiments, the method provides, for example, a hull, sabot, or wad comprising crosslinked polyethylene, propylene, butylene, or combinations thereof. In other embodiments, the hull, sabot, or wad is made from crosslinked high-density polyethylene. One example of a disclosed embodiment is a hull, sabot or wad made by crosslinking high-density polyethylene during an extrusion process.

[0013] 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

[0014] Non-limiting and non-exhaustive examples are described with reference to the following figures.

[0015] FIG. 1 is a conceptual diagram illustrating a sectional view of a shotgun shell.

[0016] FIG. 2A is a conceptual diagram illustrating a cutaway, cross-sectional view of a shotgun shell with a pusher plate.

[0017] FIG. 2B is a conceptual diagram illustrating a cutaway, cross-sectional view of a shotgun shell without a pusher plate.DETAILED DESCRIPTION

[0018] The following description sets forth exemplary aspects of the present disclosure. It should be recognized, however, that such description is not intended as a limitation on the scope of the present disclosure. Rather, the description also encompasses combinations and modifications to those exemplary aspects described herein.

[0019] In one embodiment the disclosed polymeric ammunition has the following principal components: a substantially cylindrical primer assembly having a base having a top surface opposite a bottom surface, a substantially cylindrical coupling flange that extends from the top surface forming a substantially cylindrical inner surface, a substantially cylindrical primer wall that extends from the bottom surface. The substantially cylindrical primer recess is formed by the inner surface of the substantially cylindrical primer wall such that the substantially cylindrical inner surface is opposite the substantially cylindrical primer recess, and a primer aperture formed through the base to connect the substantially cylindrical inner surface to the substantially cylindrical primer recess; a substantially cylindrical polymeric middle body of hull having the substantially cylindrical primer insert at a first end and a substantially cylindrical polymeric region at a second end by contacting a selected crosslinked polymeric material with the substantially cylindrical primer insert, wherein theAttorney Docket No.: 421.23644-WOpolymeric material covers the substantially cylindrical coupling flange and extends over the substantially cylindrical inner surface to form a primer flash hole and extends over the outer surface of the substantially cylindrical primer wall. A propellant chamber extends from the substantially cylindrical polymeric coupling region to the primer flash aperture coupling a substantially cylindrical polymeric projectile-end component to the substantially cylindrical polymeric middle body. The substantially cylindrical polymeric projectile-end component comprises a substantially cylindrical polymeric coupling end opposite a projectile aperture, wherein the substantially cylindrical polymeric coupling end mates to the substantially cylindrical polymeric coupling region and extends the propellant chamber from the projectile aperture to the primer flash hole; and positioning a propellant insert in the propellant chamber to reduce the internal volume of the propellant chamber.

[0020] The substantially cylindrical polymeric middle body, the substantially cylindrical polymeric projectile-end component and the propellant insert independently may include a material selected from the group consisting of, for example, crosslinked polyolefins, polyphenylsulfone, polycarbonate, and polyamide. The substantially cylindrical polymeric middle body, the substantially cylindrical polymeric projectile-end component and the propellant insert may independently include at least one additive selected from the group consisting of plasticizers, lubricants, molding agents, fillers, thermo-oxidative stabilizers, flame-retardants, coloring agents, compatibilizers, impact modifiers, release agents, reinforcing fibers and reinforcing agents.

[0021] Sabots used for conventional firearms are often injected molded into a single body in a simple manufacturing process that maintains a low cost per unit of ammunition.Polymers, such as high-density polyethylene, provide favorable characteristics such as engagement of barrel rifling, absorption of shock peaks from the propellant, and gas sealing. However, an inherent drawback of polymer sabots is that the polymer can unevenly axially deform, disintegrate, or destruct when subjected to the high-pressure forces used to fire the shell. In particular, the projectile seating base, such as a wad or wadding, which is intermediate or sandwiched between the projectile and the propellant charge, experiences significant compression during firing often resulting in substantial deformation. Uneven axial deformation of the wad and other parts of the sabot can generate a wobble, yaw, precession, and / or nutation of the projectile particularly after the projectile leaves the barrel resulting in diminished accuracy. Uneven deformation and disintegration also affect the uniform deployment of the wings after the sabot exits the muzzle.Attorney Docket No.: 421.23644-WO

[0022] To facilitate the understanding of this disclosure, certain terms have the following definitions and meanings. These terms have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present disclosure. Terms such as “a,” “an” and “the” are not intended to refer to only a singular entity but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the disclosure, but their usage does not delimit the disclosure, except as outlined in the claims. As used herein, the term ammunition,” “ammunition article,” “munition,” and “munition article” are used interchangeably to refer to a complete, assembled round or shell that is ready to be loaded into a firearm and fired, including cap, casing, propellant, projectile, etc. Ammunition may be a live round fitted with a projectile, or a blank round with no projectile and may also be other types such as non-lethal rounds, rounds containing rubber projectiles, rounds containing multiple projectiles (shot). The terms hull, casing, case, and body may be used interchangeably (for example, the terms shell casing, shell case and casing body) to refer to the portion of the ammunition that remains intact after firing and includes the propellant chamber and may include the primer insert. A shell casing may be one-piece, two-piece, three piece or multi-piece design that includes a mouth at one end and a primer insert at the other separated by a propellant chamber. A traditional shell casing generally has an elongated body with a primer end and a projectile end.

[0023] During use, a firearm supports the shell casing wall in the radial direction, however, in many firearms, a portion of the shell base end is unsupported. During firing, the greatest stresses are concentrated at the base end of the shell, which must have characteristics and properties that will consistently and safely handle the concentration of these stresses placed on the shell during the loading and firing sequences.

[0024] One skilled in the art will also readily observe that different or identical coloring of the polymers used could aid in identification or marketing of the ammunition of the current disclosure. Another embodiment of this disclosure would be the usage of transparent or translucent polymers, allowing for easy identification of the propellant level or shell load.

[0025] A non-limiting list of suitable polymeric materials, for both the shell casing, wad or sabot may be selected from any number of polymeric materials and individual monomers of a copolymer include, for example, polybutylene terephthalates, polyamides, poly-imides, polyesters, polycarbonates, polysulfones, polylactones, polyacetals, acrylonitrile / butadiene / styrene copolymer resins, polyphenylene oxides, ethylene / carbon monoxide copolymers, polyphenylene sulfides, polystyrene, styrene / acrylonitrile copolymer resins, styrene / maleic anhydride copolymer resins, aromatic polyketones, and mixturesAttorney Docket No.: 421.23644-WOthereof. Preferred embodiments will be manufactured from any polymer having a glass transition temperature of less than 250°C. Particularly suitable materials include crosslinked polyolefins, polyphenylsulfones, polycarbonates and polyamides.

[0026] FIG. 1 is a conceptual diagram illustrating an example shotgun shell 100. The shotgun shell 100 includes a head 101 and a casing 102 extending from a forward end 106 to a rearward end 114 and defining a chamber 104. The casing 102 may be formed from an extruded crosslinked polyolefin. In some examples, the casing 102 may include a translucent or transparent polymer. Chamber 104 is configured to retain a propellant 108, a wad 110, an optional back wad 112, and one or more projectile 118. In some examples, additional components may be housed in chamber 104, such as a pusher plate, sabot, or the like.

[0027] Head 101 is coupled to the casing 102 along an interface 116. In some examples, interface 116 may define a mechanical coupling, an adhesive, or a combination thereof. Interface 116 is configured to withstand heat and pressure produced during ignition of propellant 108. For example, during ignition of propellant 108, the cook-off temperature of propellant 108 may reach approximately 320°F to approximately 338°F and pressures may exceed 11,500 pounds per square inch (psi).

[0028] Head 101 is also configured to receive a primer assembly 130. Primer assembly 130 positioned a primer within chamber 104 that is configured to ignite propellant 108.

[0029] The chamber 104 houses several internal components arranged in a specific order. A propellant 108 is adjacent and supported by a wad 110 and an optional back wad 112. Wad 110 is positioned within the casing 102 above the propellant 108 and provides separation between the propellant 108 and a load including one or more projectiles 118. Back wad 112 is positioned within the casing 102 below the propellant 108 and supports head 101 during ignition of propellant 108. Wad 110, back wad 112, or both may be formed from an extruded or an injection molded crosslinked polyolefin.

[0030] Projectiles 118 are positioned forward of wad 110 and extend toward the forward end 106 of the casing 102. Projections 118 may include shot or other projectiles. In some examples, wad 110 may facilitate discharge of projectiles 118 through the barrel of the firearm, during at least a portion of flight after muzzle exit, or both. For example, wad 110 may include wads described in U.S. Patent No. 9,778,002, the entire disclosure of which is incorporated by reference herein.

[0031] Each of casing 102, wad 110, and optional back wad 112 may include polymer-based components suitable to be formed by injection molding or other plastic forming techniques. These polymer-based components may be compatible for direct contact withAttorney Docket No.: 421.23644-WOpropellant 108. Additionally, the polymer-based components may be resistant to gun cleaning solvents and grease, as well as resistant to chemical, biological and radiological agents.

[0032] The polymeric materials of the described components have a temperature resistance higher than the cook-off temperature of the propellant, typically approximately 320°F to approximately 338°F. Additionally, the polymeric materials have elongation-to-break values that resist deformation under interior ballistic pressure up to approximately 11,500 pounds per square inch (psi); such as up to approximately 20,000 psi, or even up to approximately 60,000 psi in all environments (temperatures from approximately -65°F to approximately 320°F and humidity from 0% to 100% RH).

[0033] In some examples, the polymeric materials of the described components include crosslinked polyolefins such as, for example, polyethylene, or polypropylene. These polymers are crosslinked with radiation or free radical-producing agents including, but not limited to, azo-, peroxide-, or silane- agents. For example, the polymeric materials may include a modified ZYTEL® resin, available from E.I. DuPont De Nemours Co., a modified nylon resin, or other polymers modified to increase elastic response.

[0034] Additionally, or alternatively, the polymeric materials of the described components may include polyphenylsulfones; copolymers of polyphenylsulfones with polyether-sulfones or poly- sulfones; copolymers and blends of polyphenylsulfones with polysiloxanes; poly(etherimide-siloxane); copolymers and blends of polyetherimides and poly siloxanes, and blends of polyetherimides and poly(etherimide-siloxane) copolymers; and the like. Specific examples include crosslinked polyolefins, polyphenylsulfones and their copolymers with poly-sulfones, or polysiloxanes that have high tensile strength and elongation-to-break to sustain the deformation under high interior ballistic pressure. Some of these types of polymers are commercially available, for example, RADEL® R5800 polyphenylsulfone from Solvay Advanced Polymers.

[0035] Other examples of suitable polymeric materials include polyurethane pre-polymer, cellulose, fluoropolymer, ethylene inter-polymer alloy elastomer, ethylene vinyl acetate, nylon, polyether imide, polyester elastomer, polyester sulfone, polyphenyl amide, polypropylene, polyvinylidene fluoride or thermoset polyurea elastomer, acrylics, homopolymers, acetates, copolymers, acrylonitrile-butadiene-styrene, thermoplastic fluoropolymers, ionomers, polyamides, polyamide-imides, polyacrylates, poly etherketones, polyarylsulfones, polybenzimidazoles, polycarbonates, polybutylene, terephthalates, polyether imides, polyether sulfones, thermoplastic polyimides, thermoplastic polyurethanes,Attorney Docket No.: 421.23644-WOpolyphenylene sulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides, styrene acrylonitriles, polystyrenes, polyphenylene, ether blends, styrene maleic anhydrides, polycarbonates, allyls, aminos, cyanates, epoxies, phenolics, unsaturated polyesters, bismaleimides, polyurethanes, silicones, vinylesters, or urethane hybrids. Examples of suitable polymeric materials also include aliphatic or aromatic polyamide, polyeitherimide, polysulfone, polyphenylsulfone, polyphenylene oxide, liquid crystalline polymer and polyketone.

[0036] The above-described polymeric materials can be formulated with up to approximately 10 wt% of one or more additives selected from cross-linking agents (e.g., organic peroxides, dicumyl peroxide, glutaraldehyde, diisocyanates, carbodiimides, polyepoxy compounds, or the like), internal mold release agents, heat stabilizers, anti-static agents, colorants, impact modifiers, and UV stabilizers.

[0037] In some examples, the described polymeric materials may include one or more composite-forming materials including, but not limited to, tungsten powder, other metal powders, glass fiber, ceramic fiber, carbon fiber, mineral fillers, organo-nano clay, or carbon nanotubes. In some examples, the composite-forming materials can be within a range from approximately 0.5 weight percent (wt%) to approximately 75 wt% based on the weight of the polymeric material. In some examples, the composite-forming materials may include one or more filler materials included a range from approximately 0.5 wt% to approximately 15 wt%, such as within a range from approximately 1 wt% to approximately 12 wt%, or within a range from approximately 2 wt% to approximately 9 wt%. Alternatively, the compositeforming materials may be included in amounts less than approximately 10 wt%. In some examples, the composite-forming materials may include one or more reinforcing materials included a range from approximately 30 wt% to approximately 75 wt%, such as approximately 65 wt%. For example, a polymeric material may include one or more polyolefins or polyphenylsulfones reinforced with approximately 30 wt% to approximately 70 wt%, and preferably up to approximately 65 wt% of one or more reinforcing materials selected from glass fiber, ceramic fiber, carbon fiber, mineral fillers, organo-nano clay, or carbon nanotubes. Suitable reinforcing materials, such as chopped surface-treated E-glass fibers, provide flow characteristics at the above-described loadings comparable to unfilled polymers to provide a desirable combination of strength and flow characteristics that permit the molding of head-end components.

[0038] In some examples, polymeric materials and optional composite materials suitable for molding of the described polymer-based components have one or more of the followingAttorney Docket No.: 421.23644-WOproperties: yield or tensile strength at -65°F of greater than approximately 10,000 psi, elongation-to-break at -65 °F of greater than approximately 15%, yield or tensile strength at 73°F of greater than approximately 8,000 psi elongation-to-break at 73°F of greater than approximately 50%, yield or tensile strength at 320°F of greater than approximately 4,000 psi, elongation-to-break at 320°F of greater than approximately 80%.

[0039] In some examples, the polymeric material additionally includes at least one additive selected from plasticizers, lubricants, molding agents, fillers, thermo-oxidative stabilizers, flame-retardants, coloring agents, compatibilizers, impact modifiers, release agents, reinforcing fibers. In still another such embodiment, the polymeric material comprises a material selected from the group consisting of crosslinked polyolefins, polyphenyl sulfones, polycarbonates, and polyamides. In such an embodiment, the polymeric material may include a translucent or transparent polymer. In another such embodiment, the polymeric material may include a polymeric material possessing a glass transition temperature of less than 250°C.

[0040] The polymers of the present disclosure can also be used for conventional two-piece metal-plastic hybrid shell case designs and conventional shotgun shell designs. One example of such a design is an ammunition shell that is made with, for example, a one-piece substantially cylindrical polymeric shell casing body with an open projectile-end and an end opposing the projectile-end with a male or female coupling element; fitted to a cylindrical metal shell primer assembly component with an essentially closed base end with a primer aperture opposite an open end having a coupling element that is a mate for the coupling element on the opposing end of the polymeric shell casing body joining the open end of the head-end component to the opposing end of the polymeric shell casing body. The high polymer ductility permits the propellant chamber 108 that is opposite a top surface 106. The substantially cylindrical hull 102 includes a primer assembly 130 positioned in the bottom surface 114 with a primer flash aperture located in the primer recess and extends through the bottom surface 114 into propellant chamber 108 to combust the propellant in the propellant chamber. A primer of the primer assembly 130 extends through the bottom surface 114 into the propellant chamber 108. The interior volume of propellant chamber 108 may be varied to provide the volume necessary for complete filling of the propellant chamber 108 by the propellant chosen so that a simplified volumetric measure of propellant can be utilized when loading the shell.

[0041] Cross-linked polyethylene can have significantly enhanced chemical, thermal and mechanical properties when compared to modified polyethylene. Improving the impactAttorney Docket No.: 421.23644-WOstrength at low temperatures as well as maintaining high strength and hardness at elevated temperatures provides significant advantage in polymer-based shotgun shell components. These components undergo significant stresses during a ballistic event and are exposed to a variety of harsh environmental conditions. In one example, a shotgun shell sabot for copper slugs uses an aluminum pusher plate or component to support the base of the slug in order to not crush the plastic sabot during firing. To eliminate the expensive aluminum component, crosslinked polyethylene sabots cross-linked with e-beam radiation were tested. During the accuracy testing at temperatures including ambient, 0°F, and 130°F, surprising accuracy results are observed. Very consistent accuracy was achieved across this temperature spectrum, especially at 130°F when failure occurred in shells without the use of the aluminum component. It is desirable that a shotgun shell have the following properties and characteristics when made as set out in this disclosure including material thickness range for shotshell components: (0.015” - 0.200”), acceptable operating pressure ranges (9,000 to 15,000 PSI, if applied to Muzzleloader parts pressures increase to: 27,000 PSI), and operating range for extreme temperatures: -20°F to +130°F.

[0042] In selected embodiments where a crosslinked, extruded polyolefin is used to make a shotgun hull as set out in this disclosure, such a shotgun shell has, for example, increased reloadability of hull with improved toughness, better performance at temperature extremes (e.g., cold temps can cause split tubes and / or circumferential cut-offs), improved mechanical properties allowing for a decreased tube thickness and reduce plastic usage.

[0043] In selected embodiments where a crosslinked, extruded polyolefin is used to make a shotgun wadding as set out in this disclosure, such a shotgun shell has, for example, lighter components and less plastic usage with crosslinked polyethylene. This provides lighter components to reduce payload weight, therefore requiring less propellant and lowering recoil, and more room for payload with less plastic needed.

[0044] Cross-linked polyethylene can provide for a completely injection molded hull. Further, cross-linking opens the door for use of lower cost polyethylene but still achieves the desired performance for the shot gun shell. In these embodiments, cross-linking can make polyethylene more susceptible to degradation from UV light.

[0045] FIGS. 2A and 2B illustrate a cut-away, cross section view of a shot shell 200 that includes a sabot 210A (FIG. 2A) and 210B (FIG. 2B), a projectile 220 with tip 222, wad 230, a propellant charge 240, hull 250, head 260, primer 270 and back wad 280. FIG. 2A further illustrates a pusher plate 215 fitted between the wad 230 and sabot 210A. This pusher plate 215 provides properties in order to provide the shot gun shell to allow the sabot to properlyAttorney Docket No.: 421.23644-WOfunction during firing of the shot gun shell. In contrast, FIG. 2B illustrates a shot gun shell 200 that does not include, or is free of, a pusher plate. The sabot 210B in FIG. 2B is formed from a crosslinked polymer that has characteristics and properties allowing the shot gun shell 200 to be fired and function properly without use of a pusher plate. In selected embodiments, the sabot 21 OB is formed from crosslinked high-density polyethylene as set out in this disclosure.

[0046] As illustrated in FIG. 2A, shotgun shell 200 includes a substantially cylindrical body with several components arranged along its longitudinal axis and housed within hull 250. At the top of shell 200 is projectile 220 with pointed polymer tip 222. Below projectile 220 is sabot 210A that surrounds and supports projectile 220. Sabot 210A transitions to wad 230 positioned below it. Between wad 230 and sabot 210A is pusher plate 215 component. The central portion of shell 200 between wad 230 and back wad 280 defines propellant chamber 240. At the base of shell 200 is head 260 that houses primer assembly 270. Back wad 280 is positioned near the base above the primer.

[0047] Hull 250 may have a thickness range of approximately 0.015 inches to approximately 0.200 inches. This thickness range allows for structural integrity while maintaining appropriate weight and flexibility characteristics.

[0048] In some examples, sabot 210A, wad 230, hull 250, or pusher plate 215 may be formed from a cross-linked polyethylene. The use of cross-linked polyethylene in these components may provide improved material properties, such as enhanced strength, durability, and temperature resistance. In some examples, pusher plate 215 may include a metal, such as aluminum, which may be more expensive or difficult to manufacture compared to a pusher plate including a polymeric material.

[0049] Pusher plate 215 in this configuration serves to transfer the force generated by the expanding gases from the propellant to sabot 210A and projectile 220. For example, pusher plate 215 may help distribute the force more evenly across the base of sabot 210A, potentially improving the consistency of the projectile’s launch.

[0050] At the base of the shell, primer assembly 270 is seated within head 260. The primer initiates the firing sequence when struck, igniting the propellant in propellant chamber 240. The back wad 280 positioned above head 260 and primer assembly 270 may help protect the primer and provide additional sealing against propellant gases.

[0051] Shotgun shell 200 may be designed to operate in pressure ranges of 9,000 to 15,000 psi. This pressure range accounts for the forces generated during firing and ensures the structural integrity of the shell components. In some examples, the size and shape ofAttorney Docket No.: 421.23644-WOpropellant chamber 240 may be optimized to accommodate the desired amount of propellant while maintaining the overall dimensions of the shotgun shell and desired pressure during ignition of the propellant.

[0052] The shotgun shell may be designed to operate in temperature ranges of -20°F to +130°F. This wide temperature range ensures reliable performance in various environmental conditions, from cold storage to hot climates.

[0053] As illustrated in FIG. 2B, shotgun shell 200B includes a substantially cylindrical structure with several internal components arranged along its longitudinal axis and housed within hull 250. Shotgun shell 200B may be the same as or substantially similar to shell 200A described above in reference to FIG. 2A, except for the differences described herein. For example, in the configuration illustrated in FIG. 2B, shotgun shell 200B is free of a pusher plate between wad 230 and sabot 210B. The absence of a pusher plate may simplify the manufacturing process and reduce production costs. This design relies on the properties of the materials used for sabot 210B, wad 230, or both to effectively transfer the force from the expanding gases to projectile 220 during firing.

[0054] The use of crosslinked polymers, such as crosslinked polyethylene, for components like sabot 210B and / or wad 230 may contribute to the ability to eliminate the pusher plate. Crosslinked polymers may offer improved strength, durability, and temperature resistance compared to non-crosslinked counterparts. These enhanced material properties may allow sabot 210B and wad 230 to withstand the forces generated during firing without the need for additional support from a pusher plate.

[0055] In some examples, sabot 210B may be designed to separate from projectile 220 after exiting the muzzle of the shotgun barrel without requiring a pusher plate. This separation may be achieved through the inherent properties of the crosslinked polymer material and the design of sabot 210B. In some examples, sabot 210B may include features such as petals or segments that are configured to open and release projectile 220 upon exiting the barrel, driven by the forces acting on sabot 210B during flight.

[0056] The elimination of the pusher plate may offer several potential benefits.Manufacturing time and costs may be reduced due to the fewer components required. The simplified design may also contribute to more consistent performance, as there are fewer interfaces between components that could introduce variability.

[0057] By leveraging the properties of crosslinked polymers in components such as sabot 210B and wad 230, the shotgun shell design may achieve the necessary performance characteristics without the need for a separate pusher plate. This approach may demonstrateAttorney Docket No.: 421.23644-WOhow material selection and component design can be optimized to create more efficient and cost-effective ammunition.

[0058] The shotgun shells described herein may be manufactured by suitable technique. In some examples, shotgun shell components may be formed from an extruded crosslinked polyolefin. The crosslinked polyolefin may be polyethylene, polypropylene, polybutylene, or combinations thereof. In some examples, the crosslinked polyolefin may be high-density polyethylene. This material choice may provide improved durability and performance characteristics compared to non-crosslinked polymers. The crosslinked polyolefin shotgun shell components may exhibit enhanced resistance to deformation under the high pressures and temperatures experienced during firing.

[0059] A wad of a shotgun shell may be formed from a crosslinked polyolefin. The use of crosslinked polyolefin for the wad may allow for improved cushioning and gas sealing properties, potentially enhancing the overall performance of the shotgun shell.

[0060] A sabot for a shotgun shell may include a body formed from an extruded crosslinked polyolefin. The sabot may include a projectile-receiving portion configured to hold a projectile and a base portion configured to interface with a propellant charge. In some examples, the crosslinked polyolefin of the sabot may be high-density polyethylene.

[0061] The projectile-receiving portion of the sabot may comprise a plurality of petals configured to separate upon firing of the shotgun shell. This design may facilitate the release of the projectile after exiting the barrel while maintaining a secure hold during the firing process.

[0062] The base portion of the sabot may comprise a gas seal configured to prevent propellant gases from passing between the sabot and an inner surface of a shotgun barrel. This gas seal may help maximize the transfer of energy from the propellant gases to the projectile, potentially improving overall performance.

[0063] Crosslinking of the polyolefin may be achieved through various techniques. In some examples, the crosslinked polyolefin may be crosslinked using radiation. Alternatively, the crosslinking process may involve the use of a cross-linking agent, such as, peroxide, silane, or azo compounds. The choice of crosslinking method may depend on the specific material properties desired and the manufacturing process employed.

[0064] The polymeric material used for shotgun shell components may have a glass transition temperature of less than 250°C. This characteristic may contribute to the material’s ability to maintain desirable properties across a range of operating temperatures.Attorney Docket No.: 421.23644-WO

[0065] In some examples, the polymeric material may include additives to further enhance its properties. These additives may include plasticizers, lubricants, molding agents, fillers, thermo-oxidative stabilizers, flame-retardants, coloring agents, compatibilizers, impact modifiers, release agents, or reinforcing fibers. The selection and combination of these additives may be tailored to achieve specific performance characteristics for different shotgun shell components.

[0066] The use of crosslinked polyolefins in shotgun shell components may offer several potential advantages. These materials may provide improved strength and durability compared to non-crosslinked polymers, potentially extending the lifespan of the components. The enhanced material properties may also allow for the design of lighter weight components without sacrificing performance, potentially reducing overall ammunition weight.

[0067] In some examples, the use of crosslinked polyolefins may enable the simplification of shotgun shell designs. For example, the improved strength and impact resistance of these materials may allow for the elimination of certain reinforcing components, potentially reducing manufacturing complexity and costs.

[0068] The combination of material properties offered by crosslinked polyolefins may contribute to more consistent performance across a range of environmental conditions. This consistency may be particularly beneficial for maintaining reliable function in extreme temperatures or harsh environments.

[0069] The manufacturing process for creating shotgun shell components using crosslinked polyolefins may involve several steps and techniques. In some examples, the process may begin with the formation of the hull from a crosslinked polyolefin. This may be accomplished through an extrusion process, where the polyolefin material is heated and forced through a die to create a continuous tubular shape. The crosslinking of the polyolefin may occur during the extrusion process, which may involve the addition of crosslinking agents or the application of radiation to initiate the crosslinking reaction.

[0070] In some examples, the hull may be formed by molding instead of extrusion. This process may involve injecting the polyolefin material into a mold cavity shaped like the desired hull. Crosslinking may occur during or after the molding process, depending on the specific technique employed.

[0071] After forming the hull, a head may be coupled to the hull. This coupling process may involve mechanical attachment methods, such as friction fitting or crimping, or may utilize adhesive bonding techniques. The choice of coupling method may depend on the specific design requirements and the materials used for the base and hull.Attorney Docket No.: 421.23644-WO

[0072] The manufacturing process may then involve inserting a primer into the base. This step may require precise positioning and secure attachment of the primer to ensure proper function during firing.

[0073] Loading of the propellant into the hull may follow the primer insertion.Alternatively, a back wad may be positioned in the hull prior to loading the propellant. The amount and type of propellant may be carefully measured and deposited into the hull to achieve the desired ballistic performance.

[0074] A wad may be positioned within the hull above the propellant. In some examples, the wad may be formed from a crosslinked polyolefin. The manufacturing process for the wad may be similar to that of the hull, involving either extrusion or molding techniques. The use of crosslinked polyolefin for the wad may eliminate the need for additional components such as an aluminum pusher plate in some sabot slug designs.

[0075] The final steps in the assembly process may involve loading one or more projectiles into the hull above the wad and crimping the end of the hull to retain the one or more projectiles. The type and amount of projectile may be determined based on the specific ammunition requirements. For example, the projectile may include a slug having a sabot or shot.

[0076] Throughout the manufacturing process, the use of crosslinked polyolefins may contribute to enhanced properties of the final product. The crosslinking process may improve the material’s strength, temperature resistance, and dimensional stability. These improved properties may allow for the simplification of certain designs, such as the elimination of reinforcing components In some examples.

[0077] The manufacturing process may also include quality control measures to ensure consistency and reliability of the produced shotgun shells. These measures may involve testing for proper assembly, dimensional accuracy, and performance characteristics.

[0078] In some examples, the manufacturing process may be optimized to take advantage of the unique properties of crosslinked polyolefins. For example, the improved strength and durability of these materials may allow for thinner wall thicknesses in certain components, potentially reducing overall weight and material usage.

[0079] The specific parameters of the manufacturing process, such as extrusion temperatures, molding pressures, and crosslinking conditions, may be carefully controlled to achieve the desired material properties and component performance. These parameters may be adjusted based on the specific polyolefin material used and the requirements of the final product.Attorney Docket No.: 421.23644-WO

[0080] The following clauses

[0081] Clause 1. A shotgun shell comprising at least one of a crosslinked polyolefin hull, sabot, or wad.

[0082] Clause 2. The shotgun shell of clause 1, wherein the crosslinked polyolefin is polyethylene, propylene, butylene, or combinations thereof.

[0083] Clause 3. The shotgun shell of clause 1, wherein the crosslinked polyolefin is high-density polyethylene.

[0084] Clause 4. The shotgun shell of clause 1, wherein the crosslinked polyolefin is crosslinked using radiation.

[0085] Clause 5. The shotgun shell of clause 1, wherein the crosslinked polyolefin is crosslinked using peroxide, silane, or azo compounds.

[0086] Clause 6. The shotgun shell of clause 1, wherein the crosslinked polyolefin is crosslinked during extrusion.

[0087] Clause 7. The shotgun shell of clause 1, wherein the crosslinked polyolefin is crosslinked after extrusion.

[0088] Clause 8. A shotgun shell comprising a base, a primer, a propellant, a wad, shot, and a hull, wherein the hull, sabot, or wad comprises a crosslinked polyolefin.

[0089] Clause 9. The shotgun shell of clause 8, wherein the hull, sabot, or wad comprises crosslinked high-density polyethylene.

[0090] Clause 10. The shotgun shell of clause 8, wherein the shotgun shell is free of a pusher plate.

[0091] Clause 11. A method of making a shotgun shell, wherein the method comprises forming at least one of a hull, sabot, or wad of the shotgun shell from a crosslinked polyolefin.

[0092] Clause 12. The method of clause 11, wherein forming the hull, sabot or wad comprises extruding the crosslinked polyolefin to form the hull, sabot, or wad.

[0093] Clause 13. The method of clause 11, wherein forming the hull, sabot, or wad comprises injection molding the crosslinked polyolefin to form the hull, sabot, or wad.

[0094] Clause 14. The method of clause 11, wherein the hull, sabot or wad comprises crosslinked polyethylene, propylene, butylene, or combinations thereof.

[0095] Clause 15. The method of clause 11, wherein the hull, sabot, or wad comprises crosslinked high-density polyethylene.

[0096] Clause 16. The method of clause 11, wherein the hull is formed by crosslinking high-density polyethylene during an extrusion process.Attorney Docket No.: 421.23644-WO

[0097] Clause 17. A shotgun shell comprising: a hull formed from an extruded crosslinked polyolefin; a head coupled to the hull; a primer disposed in the head; a propellant contained within the hull; a wad positioned within the hull above the propellant; and a projectile contained within the hull above the wad.

[0098] Clause 18. The shotgun shell of clause 17, wherein the crosslinked polyolefin is polyethylene, polypropylene, polybutylene, or combinations thereof.

[0099] Clause 19. The shotgun shell of clause 18, wherein the crosslinked polyolefin is high-density polyethylene.

[0100] Clause 20. The shotgun shell of clause 17, wherein the crosslinked polyolefin is crosslinked using radiation.

[0101] Clause 21. The shotgun shell of clause 17, wherein the crosslinked polyolefin is crosslinked using peroxide, silane, or azo compounds.

[0102] Clause 22. The shotgun shell of clause 17, wherein the wad is formed from a crosslinked polyolefin.

[0103] Clause 23. The shotgun shell of clause 22, wherein the shotgun shell is free of a pusher plate between the wad and the projectile.

[0104] Clause 24. A method of making a shotgun shell, comprising: forming a hull from a crosslinked polyolefin; coupling a head to the hull; inserting a primer into the head; loading a propellant into the hull; positioning a wad within the hull above the propellant; and loading a projectile into the hull above the wad.

[0105] Clause 25. The method of clause 24, wherein forming the hull comprises extruding the crosslinked polyolefin.

[0106] Clause 26. The method of clause 25, wherein the crosslinked polyolefin is crosslinked during the extrusion process.

[0107] Clause 27. The method of clause 24, wherein the crosslinked polyolefin is high-density polyethylene.

[0108] Clause 28. The method of clause 24, further comprising forming the wad from a crosslinked polyolefin.

[0109] Clause 29. The method of clause 28, wherein the method does not include positioning a pusher plate between the wad and the projectile.

[0110] Clause 30. The method of clause 24, wherein the crosslinked polyolefin is crosslinked using radiation, peroxide, silane, or azo compounds.Attorney Docket No.: 421.23644-WO

[0111] Clause 31. A sabot for a shotgun shell, comprising: a body formed from an extruded crosslinked polyolefin; a projectile-receiving portion configured to hold a projectile; and a base portion configured to interface with a propellant charge.

[0112] Clause 32. The sabot of clause 31, wherein the crosslinked polyolefin is high-density polyethylene.

[0113] Clause 33. The sabot of clause 32, wherein the high-density polyethylene is crosslinked using radiation.

[0114] Clause 34. The sabot of clause 31, wherein the projectile-receiving portion comprises a plurality of petals configured to separate upon firing of the shotgun shell.

[0115] Clause 35. The sabot of clause 34, wherein the base portion comprises a gas seal configured to prevent propellant gases from passing between the sabot and an inner surface of a shotgun barrel.

[0116] Clause 36. The sabot of clause 35, wherein the sabot is configured to separate from a projectile after exiting a muzzle of the shotgun barrel without requiring a pusher plate.

[0117] illustrate example subject matter described herein.

[0118] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.

Claims

Attorney Docket No.: 421.23644-WOCLAIMSWhat is claimed is:

1. A sabot for a shotgun shell, comprising:a body formed from a crosslinked high-density polyethylene;a projectile-receiving portion comprising a plurality of petals configured to hold a projectile and to separate upon firing of the shotgun shell; anda base portion comprising a gas seal configured to interface with a propellant charge and to prevent propellant gases from passing between the sabot and an inner surface of a shotgun barrel,wherein the sabot is configured to function without a pusher plate.

2. The sabot of claim 1, wherein the crosslinked high-density polyethylene has a density greater than 0.94 g / cm3.

3. The sabot of claim 2, wherein the high-density polyethylene is crosslinked using radiation.

4. The sabot of claim 1, wherein the plurality of petals are configured to open and release the projectile upon exiting a barrel of a firearm.

5. The sabot of claim 4, wherein the sabot is configured to maintain dimensional stability at temperatures up to 130°F.

6. The sabot of claim 5, wherein the sabot is configured to separate from a projectile after exiting a muzzle of the shotgun barrel without requiring a pusher plate, and wherein the crosslinked high-density polyethylene is crosslinked during an extrusion process.Attorney Docket No.: 421.23644-WO7. A shotgun shell comprising:ahull;a propellant contained within the hull;a wad positioned within the hull; anda sabot formed from a crosslinked polyolefin and configured to hold a projectile, wherein the shotgun shell is free of a pusher plate between the wad and the sabot.

8. The shotgun shell of claim 7, wherein the crosslinked polyolefin is polyethylene, propylene, butylene, or combinations thereof, and wherein the sabot is configured to operate in a temperature range of -20°F to +130°F.

9. The shotgun shell of claim 7, wherein the crosslinked polyolefin is high-density polyethylene.

10. The shotgun shell of claim 7, wherein the crosslinked polyolefin is crosslinked using electron beam radiation.

11. The shotgun shell of claim 7, wherein the crosslinked polyolefin is crosslinked using peroxide, silane, or azo compounds.

12. The shotgun shell of claim 7, wherein the crosslinked polyolefin is crosslinked during extrusion.

13. The shotgun shell of claim 7, wherein the crosslinked polyolefin is crosslinked after extrusion.Attorney Docket No.: 421.23644-WO14. A shotgun shell comprising:a head;a primer disposed in the head;a hull coupled to the head;a propellant contained within the hull;a back wad positioned within the hull adjacent the propellant;a wad positioned within the hull above the propellant; anda sabot formed from a crosslinked high-density polyethylene and configured to hold a projectile,wherein the shotgun shell is free of a pusher plate between the wad and the sabot.

15. The shotgun shell of claim 14, wherein the hull, sabot, and wad each comprise crosslinked high-density polyethylene, and wherein the wad is configured to transfer force from expanding propellant gases to the sabot without a pusher plate.

16. The shotgun shell of claim 14, wherein the sabot comprises a plurality of petals configured to separate upon firing of the shotgun shell.

17. A shotgun shell comprising:a hull formed from an extruded crosslinked polyolefin;a head coupled to the hull;a primer disposed in the head;a propellant contained within the hull;a wad positioned within the hull above the propellant;a projectile contained within the hull above the wad; anda sabot formed from a crosslinked polyolefin positioned between the wad and the projectile,wherein the shotgun shell is free of a pusher plate between the wad and the sabot.

18. The shotgun shell of claim 17, wherein the crosslinked polyolefin is polyethylene, polypropylene, polybutylene, or combinations thereof, and wherein the shotgun shell is configured to operate at pressures in a range from 9,000 psi to 15,000 psi.Attorney Docket No.: 421.23644-WO19. The shotgun shell of claim 18, wherein the crosslinked polyolefin is high-density polyethylene.

20. The shotgun shell of claim 17, wherein the crosslinked polyolefin is crosslinked using radiation.

21. The shotgun shell of claim 17, wherein the crosslinked polyolefin is crosslinked using peroxide, silane, or azo compounds.

22. The shotgun shell of claim 17, wherein the wad is formed from a crosslinked polyolefin and is configured to provide gas sealing between the propellant and the projectile.

23. The shotgun shell of claim 22, wherein the shotgun shell is free of a pusher plate between the wad and the projectile, and wherein the wad is formed from crosslinked high-density polyethylene.

24. A method of making a shotgun shell, wherein the method comprises:forming a sabot from a crosslinked polyolefin by crosslinking the polyolefin during an extrusion process;positioning the sabot within a hull of the shotgun shell; andassembling the shotgun shell without a pusher plate between a wad and the sabot.

25. The method of claim 24, wherein forming the hull, sabot or wad comprises extruding the crosslinked polyolefin to form the hull, sabot, or wad.

26. The method of claim 24, wherein forming the hull, sabot, or wad comprises injection molding the crosslinked polyolefin to form the hull, sabot, or wad.

27. The method of claim 24, wherein the hull, sabot or wad comprises crosslinked polyethylene, propylene, butylene, or combinations thereof, and wherein the sabot has a material thickness in a range from 0.015 inches to 0.200 inches.Attorney Docket No.: 421.23644-WO28. The method of claim 24, wherein the hull, sabot, or wad comprises crosslinked high-density polyethylene.

29. The method of claim 24, wherein the hull is formed by crosslinking high-density polyethylene during an extrusion process.

30. A method of making a shotgun shell, comprising:forming a hull from a crosslinked polyolefin;coupling a head to the hull;inserting a primer into the head;loading a propellant into the hull;positioning a wad within the hull above the propellant;loading a projectile into the hull above the wad; andpositioning a sabot formed from a crosslinked polyolefin between the wad and the projectile without including a pusher plate between the wad and the sabot.

31. The method of claim 30, wherein forming the hull comprises extruding the crosslinked polyolefin.

32. The method of claim 31, wherein the crosslinked polyolefin is crosslinked during the extrusion process.

33. The method of claim 30, wherein the crosslinked polyolefin is high-density polyethylene.

34. The method of claim 30, further comprising forming the wad from a crosslinked polyolefin by crosslinking the polyolefin during an extrusion or injection molding process.

35. The method of claim 34, wherein the method does not include positioning a pusher plate between the wad and the projectile.

36. The method of claim 30, wherein the crosslinked polyolefin is crosslinked using radiation, peroxide, silane, or azo compounds.

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