Interrupted action firearm mechanism

Abstract

An interrupted action firearm mechanism comprises a trigger, a hammer, a bolt, a catch, a primary sear between the trigger and the hammer, and a secondary sear between the hammer and the bolt. Disengagement of the primary sear releases the hammer to discharge a cartridge. The bolt recoils and is held in the rearward position by the catch, preventing self-loading or semi-automatic function until manually released. The secondary sear prevents the bolt from returning if the primary sear is disengaged and the catch is held down. Resetting the mechanism requires manually pulling back the bolt, allowing the secondary sear to disengage and the primary sear to reengage once the trigger is released. The primary sear's engagement prevents the secondary sear's engagement when the hammer is released.

Description

Interrupted action firearm mechanismField of the Invention

[0001] The present invention generally pertains to semi-automatic firearms, specifically focusing on an interrupted-type semi-automatic action.Background of the Invention

[0002] A semi-automatic firearm is designed to fire one round with each pull of the trigger while automatically loading a new cartridge into the chamber for subsequent shots. This action type is highly valued for its rapid operation and minimal user input, though it is subject to legal restrictions in certain jurisdictions.

[0003] A standard semi-automatic firearm operates as follows: the shooter inserts a loaded magazine into the magazine well, and the first cartridge is pushed into the chamber by the firearm's action. When the trigger is pulled, the trigger mechanism releases the sear, allowing the hammer to strike the primer of the cartridge in the chamber. This ignites the primer, causing a small explosion that ignites the gunpowder in the cartridge case. The expanding gas propels the bullet down the barrel and out of the firearm.

[0004] As the bullet travels down the barrel, the firearm experiences recoil, which is harnessed to cycle the action. The bolt moves backward, unlocking from the barrel, and extracts and ejects the spent cartridge case. Upon reaching its rearward position, the bolt compresses a recoil spring. The spring's pressure then propels the bolt forward, picking up a new round from the magazine and chambering it. Simultaneously, the bolt resets the trigger, preparing the firearm for the next shot. This cycle of firing, extracting, ejecting, and chambering continues with each trigger pull until the magazine is empty.

[0005] However, to comply with firearm restrictions in certain jurisdictions, interrupted semi-automatic actions have been developed. These actions operate by firing a cartridge and ejecting the spent brass, but then it locks the bolt in the open / rearward breech position. The action remains in this position until the shooter releases the trigger and manually intervenes to release the bolt, allowing it to return to the forwardclosed breech position. As the bolt travels into battery, it automatically loads a new cartridge into the chamber. This interrupted action must be repeated each time the firearm is discharged.

[0006] US 20200182575 A1 (Barrett et aL, 2020-06-1 1 ), referred to hereinafter as D1 , discloses one such interrupted action which employs a bolt release mechanism for interrupted action. Initially, the firearm is in the ready-to-fire position with the bolt in the forward closed breech position and the trigger unpulled. When the trigger is pulled, the hammer is released, striking the firing pin and discharging the firearm. The bolt moves rearward due to recoil, engaging the disconnect lever and partially engaging the hammer, locking the bolt in the rearward position to prevent automatic forward movement. To release the bolt and allow it to move forward, the user must first release the trigger, deactivating the trigger safety interlock. The user then manually actuates the bolt release mechanism by pressing the release button, which rotates the disconnect lever to disengage the hammer from the bolt. This action releases the bolt, allowing it to travel forward under spring bias to reclose the breech and chamber a new round. The cycle is then ready to repeat upon the next trigger pull. This mechanism ensures the firearm can only fire when the user manually intervenes, enhancing safety and compliance with firearm regulations.

[0007] It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country.Summary of the Disclosure

[0008] The described interrupted action firearm mechanism comprises a trigger, hammer, bolt, and catch. The mechanism defines a primary sear operative between the trigger and the hammer, and a secondary sear operative between the hammer and the bolt. Upon pulling the trigger, the primary sear disengages, releasing the hammer to discharge a cartridge. After discharge, the bolt recoils backward and is held in the rearward position by the catch acting directly on the bolt, preventing the bolt from returning forward until the catch is manually released. The mechanism also incorporates the secondary sear as a failsafe, which engages to prevent the bolt fromreturning if the trigger and the catch are intentionally held down. If the secondary sear engages, the mechanism becomes effectively locked requiring the user to manually pull back the bolt to reset the mechanism, allowing the secondary sear to disengage and the primary sear to reengage once the trigger is released. Furthermore, the engagement of the primary sear prevents the engagement of the secondary sear ensuring that the secondary sear cannot engage when the trigger is released .

[0009] The main differences between the present interrupted action firearm mechanism and the bolt release mechanism described in D1 lie in their design and operation. Whereas D1 defines a primary sear operative between the trigger and the hammer, which releases the hammer, and a secondary sear between the hammer and the bolt, which prevents the return of the bolt if the trigger is intentionally held down, it however does not include the present catch that directly engages the bolt to prevent return of the bolt following discharge until the catch is manually released. Instead, D1 employs a more complicated bolt release mechanism operated by a release button to disconnect the secondary sear. This mechanism uses a disconnection lever that pivots under the action of the release button to pull the hammer away from the bolt, disengaging the secondary sear. This arrangement is more complex compared to the present invention. Moreover, holding down the release button in D1 during discharge could cause the hammer to strike the protruding disconnection lever under full bolt recoil force, potentially destroying the mechanism.

[0010] In contrast, according to the present mechanism, the secondary sear engages as a failsafe if the trigger and the catch are intentionally held down, effectively locking the mechanism. The bolt must be pulled back to reset the mechanism, allowing the secondary sear to disengage and the primary sear to reengage once the trigger is released. Additionally, when the primary sear is engaged (i.e., when the trigger is released), the hammer is held away from the bolt, ensuring that the secondary sear cannot engage when the trigger is released. This is unlike the arrangement in D1 , where both the primary sear between the trigger and the hammer and the secondary sear between the hammer and the bolt can engage simultaneously as is shown in Fig.

[0011] Other aspects of the invention are also disclosed.Brief Description of the Drawings

[0012] Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0013] Figure 1 shows components of a firearm mechanism with interrupted blowback action in accordance with an embodiment;

[0014] Figure 2 shows a primary sear of the mechanism;

[0015] Figure 3 shows a secondary sear of the mechanism;

[0016] Figure 4 shows the mechanism when cocked;

[0017] Figure 5 shows wherein return of the bolt of the mechanism is interrupted; and

[0018] Figure 6 shows wherein the secondary sear is engaged, thereby locking the mechanism.Description of Embodiments

[0019] An interrupted action firearm mechanism comprises a trigger 10, a hammer 20, bolt 30, and a catch 70. The mechanism 100 defines a primary sear A, shown in Figure 2, operative between the trigger 10 and the hammer 20, and a secondary sear B, shown in Figure 3, operative between the hammer 20 and the bolt 30. The mechanism 100 may also have a bolt guide 40 which prevents rotation of the bolt 30 when moving back and forth. The mechanism 100 may further comprise a case ejector 60, which is held on the front of the bolt 30 by an extractor claw. When the bolt 30 travels rearward and the case ejector 60 contacts the spent case, the case ejector 60 flicks the spent case off the extractor and out of an ejection port.

[0020] Figure 4 shows the mechanism when cocked, with the primary sear A engaged, thereby holding the hammer 20 back. Figure 2 shows the primary sear A in further detail, where a front edge 1 1 of a distal arm 12 of the trigger 10 is configured to engage a radial edge 13 of the hammer 20. Given the orientation of Figure 2, the hammer 20 is biased clockwise by a coil spring about a pivot point 21 , while the trigger 10 is biased counterclockwise by a coil spring about a respective pivot point.

[0021] The trigger 10 comprises a tang 14 acting on the distal arm 12 about a pivot 15. Pulling the tang 14 with a finger causes the distal arm 12 to pivot downwardly, moving the front edge 1 1 away from the radial edge 13 of the hammer 20, thereby releasing the primary sear A and allowing the hammer 20 to rotate clockwise. This rotation causes a head portion 22 of the hammer to enter through a slot 31 of the bolt 30, as seen in Figure 1 , to strike a firing pin and discharge a cartridge.

[0022] Following the discharge of the cartridge, the bolt 30 recoils backwards. As shown in Figure 1 , the bolt 30 comprises an underside cam 32, which under normal operation depresses the hammer 20 to reengage the primary sear A as the cam 32 passes the hammer 20, but only when the trigger 10 is released. As the bolt 30 reaches its rearward position, it compresses a recoil spring to rebound forward.

[0023] However, as shown in Figure 5, the catch 70 is configured to directly engage the bolt 30 to prevent its return until the catch 70 is manually released, thereby preventing self-loading or semiautomatic function. The catch 70 may assume a blocking configuration, shown in Figure 5, where it directly engages the bolt 30 to prevent the bolt from returning forward, and a non-blocking configuration, shown in Figure 6, where the catch 70 is disengaged from the bolt 30, allowing it to travel forward.

[0024] The catch 70 may be configured to directly engage an edge 33 of the bolt 30, such as the front edge 33 of the bolt 30 shown in Figure 5. The catch 70 may be spring-loaded, so it takes the blocking configuration when the edge 33 of the bolt 30 passes the catch 70. In the embodiment shown, the catch 70 levers a finger-operable tang 71 with respect to a distal arm 72 about a fulcrum / pivot 73. The distal arm 72 may define an edge that engages the edge 33 of the bolt 30. Depressing tang 71 causes the catch 70 to rotate about the fulcrum / pivot 73, moving the distal arm 72 out of the way of the edge 33 of the bolt 30 to allow the bolt 30 to return forward to pick up a new round from the magazine and chamber it.

[0025] The secondary sear B is designed as a failsafe mechanism in case the catch 70 is intentionally held down by the shooter. Specifically, the secondary sear B is configured to engage and prevent the return of the bolt 30 if the primary sear A isdisengaged. As can be appreciated, since recoil happens relatively quickly, if the catch 70 were intentionally held down by the shooter, the primary sear A would still be disengaged by the time the bolt 30 returned forward. Furthermore, given the configuration evident from Figure 5, the secondary sear B cannot engage if the primary sear A is engaged, thereby preventing engagement of the secondary sear B when the trigger 10 is released.

[0026] As shown in Figure 3, the secondary sear B may be formed between a catch edge 34 of the bolt 30 and an edge 35 of the hammer 20. As further shown in Figure 3, these edges may interface orthogonally with respect to the longitudinal axis of the bolt 30. As shown in Figure 6, when the primary sear A is not engaged, the hammer 20 is free to rotate clockwise so that the edge 33 of the hammer 20 engages the catch edge 34 of the bolt 30.

[0027] When the secondary sear B is engaged, the mechanism is effectively locked and resetting it requires manually pulling back the bolt 30 using a charging handle 50, allowing the cam 32 of the bolt to depress the hammer, disengaging the secondary sear B, and reengaging the primary sear A if the trigger 10 is released. Once the primary sear A is reengaged, the charging handle 50 and the catch 70 can be released to allow the bolt 30 to travel forward to chamber the new round without interference from the secondary sear B.

[0028] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required in order to practise the invention. Thus, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed as obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to best utilize the invention and various embodiments with variousmodifications as are suited to the particular use contemplated. It is intended that the following claims and their equivalents define the scope of the invention.

Claims

Claims1 . An interrupted action firearm mechanism comprising a trigger, a hammer, a bolt and a catch wherein the mechanism defines a primary sear operative between the trigger and the hammer and a secondary sear operative between the hammer and the bolt, wherein: disengagement of the primary sear releases the hammer to discharge a cartridge; the catch is configured to directly engage the bolt to prevent return of the bolt following the discharge until the catch is manually released; and the secondary sear engages to prevent return of the bolt if the primary sear is disengaged requiring resetting by pulling back the bolt and wherein engagement of the primary sear prevents simultaneous engagement of the secondary sear.

2. The mechanism as claimed in claim 1 , wherein the secondary sear is formed between an edge of the bolt and an edge of the hammer.

3. The mechanism as claimed in claim 2, wherein the edges interface orthogonally with respect to a longitudinal axis of the bolt.

4. The mechanism as claimed in claim 1 , wherein the catch engages an edge defined by the bolt.

5. The mechanism as claimed in claim 4, wherein the catch is biased to a blocking position to prevent return of the bolt and wherein the catch assumes the blocking configuration as the edge passes the catch following the discharge.Wherein the catch is spring loaded.

6. The mechanism as claimed in claim 1 , wherein the catch comprises a distal arm manually operated by a tang, wherein the distal arm catches the edge defined by the bolt when the catch is in the blocking position and wherein operation of the tang moves the distal arm away from the edge defined by the bolt.

7. The mechanism as claimed in claim 1 , wherein the bolt comprises an underside cam configured to depress the hammer to allow reengagement of the primary sear when the bolt is pulled back.

Images