IP Library › Granted Patent US 12,305,943
Granted Patent B2
US 12,305,943 · App. 18/244,561 · Granted May 20, 2025

Firearm operating mechanisms and bolt release

Inventors: James Matthew Underwood (Kennesaw, GA); Larry Cullen Underwood (Canton, GA)
F41A19/10F41A17/36F41A19/25F41A19/43F41A19/14
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Quick Facts
Patent No.
US 12,305,943
App. No.
18/244,561
Granted
May 20, 2025
Kind
B2
Abstract

An operating system for a firearm includes a trigger, a hammer, a disconnector, a pivoting arm, and a lower member. The trigger includes a lower portion, an upper portion, and a trigger pivot. The disconnector includes a lower portion, an upper portion, and a disconnector pivot. The pivoting arm includes a forward protrusion, a pivoting arm opening, and a pin extending through the pivoting arm opening. The lower member includes a lower member opening and a pin hole that is coaxial with the trigger pivot and the disconnector pivot. At least a portion of the trigger and at least a portion of the disconnector are disposed within the lower member opening. Motion of the trigger causes the forward protrusion of the pivoting arm to engage a bolt carrier group and hold the bolt carrier group in an open position.

Claims (42)

1. An operating system disposed within a receiver of a firearm, the operating system comprising:

a trigger;

a hammer;

a disconnector;

a pivoting arm, wherein at least a portion of the pivoting arm is disposed rearward of the hammer; and

a lower member, wherein at least a portion of the trigger and at least a portion of the disconnector are disposed adjacent to the lower member,

wherein motion of the trigger causes a forward protrusion of the pivoting arm to engage a bolt carrier group of the firearm and hold the bolt carrier group in an open position.

2. The operating system of claim 1 , further comprising a disconnector plate, a cam, and a reset arm, wherein:

the disconnector plate is disposed adjacent to the disconnector and comprises a pivot hole that is coaxial with a trigger pivot and a disconnector pivot;

the cam comprises (i) a nose that interfaces with a rear interface portion of the disconnector plate and (ii) a cam pivot that is coaxial with a pin connection between the pivoting arm and the lower member; and

the reset arm comprises a notch that interfaces with a tooth of the cam.

3. The operating system of claim 1 , wherein:

the pivoting arm comprises an opening; and

at least a portion of the hammer and at least a portion of the disconnector are disposed within the opening of the pivoting arm.

4. The operating system of claim 1 , wherein the pivoting arm is attached to the lower member by a rotation pin and wherein at least a portion of the pivoting arm is disposed within an opening of the lower member.

5. The operating system of claim 1 , wherein motion of the trigger results in pressure on the pivoting arm pin causing the pivoting arm to move upward and engage the bolt carrier group of the firearm.

6. The operating system of claim 5 , wherein releasing the trigger causes the pivoting arm to move downward and disengage the bolt carrier group of the firearm.

7. The operating system of claim 5 , wherein a subsequent trigger actuation causes the pivoting arm to move downward and disengage the bolt carrier group of the firearm.

8. The operating system of claim 1 , wherein a hammer pivot is coaxial with a forward pivot hole of the lower member.

9. The operating system of claim 1 , wherein a forward protrusion of the pivoting arm interfaces with a bolt release of the firearm.

10. The operating system of claim 1 , wherein the pivoting arm comprises at least one upward protrusion, wherein the at least one upward protrusion is configured to contact an underside of the bolt carrier group of the firearm.

11. An operating system disposed within a receiver of a firearm, the operating system comprising:

a trigger;

a hammer;

a disconnector; and

a pivoting arm, wherein:

at least a portion of the pivoting arm is disposed rearward of the hammer; and

motion of the trigger causes the pivoting arm to engage a bolt carrier group of the firearm and hold the bolt carrier group in an open position.

12. The operating system of claim 11 , further comprising a lower member that is pivotably attached to the pivoting arm.

13. The operating system of claim 11 , wherein:

the pivoting arm comprises an opening; and

at least a portion of the hammer and at least a portion of the disconnector are disposed within the opening of the pivoting arm.

14. The operating system of claim 11 , wherein motion of the trigger results in pressure on the pivoting arm pin causing the pivoting arm to move upward and engage the bolt carrier group of the firearm.

15. The operating system of claim 14 , wherein releasing the trigger causes the pivoting arm to move downward and disengage the bolt carrier group of the firearm.

16. The operating system of claim 14 , wherein a subsequent trigger actuation causes the pivoting arm to move downward and disengage the bolt carrier group of the firearm.

17. The operating system of claim 11 , further comprising a disconnector plate, a cam, and a reset arm, wherein:

the disconnector plate is disposed adjacent to the disconnector and comprises a pivot hole that is coaxial with a trigger pivot and a disconnector pivot;

the cam comprises (i) a nose that interfaces with a rear interface portion of the disconnector plate and (ii) a cam pivot that is coaxial with a pin connection of the pivoting arm; and

the reset arm comprises a notch that interfaces with a tooth of the cam.

18. The operating system of claim 12 , wherein the hammer pivot is coaxial with a forward pivot hole of the lower member.

19. The operating system of claim 11 , wherein the forward protrusion of the pivoting arm interfaces with a bolt release of the firearm.

20. The operating system of claim 11 , wherein the pivoting arm comprises at least one upward protrusion, wherein the at least one upward protrusion is configured to contact an underside of the bolt carrier group of the firearm.

Continuity (4)
Continuation 17671027 · Feb 14, 2022
Continuation 16815993 · Mar 11, 2020
Provisional Application 62816476 · Mar 11, 2019
Related Publication 20230417505A1 · Dec 28, 2023
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