Firearm trigger reset assist apparatus and method
Patent No. US9021732 (titled "Firearm trigger reset assist apparatus and method") on Mar 14, 2013. The application was issued on May 5, 2015.
What is this patent about?
’732 is related to the field of firearm trigger mechanisms, specifically focusing on auxiliary components designed to facilitate the rapid reset of a trigger. In semi-automatic and pump-action firearms, the rate of fire is often limited by the user's ability to quickly release the trigger to its forward position, a process that can be hindered by physical fatigue or medical conditions like arthritis that limit finger extension.
The underlying idea behind ’732 is to harness the kinetic energy of the bolt carrier group during its rearward travel to mechanically force the trigger back into its reset position. By utilizing a specialized torsion spring as a force-translation bridge, the invention converts the movement of the cycling action into a proactive reset stroke, rather than relying solely on the internal trigger spring or the user's finger strength to clear the sear.
The claims of ’732 focus on a double torsion spring assembly mounted on a dedicated pivot pin, featuring upper arms that intercept the bolt carrier group and lower arms that are mechanically bridged to engage the trigger. This configuration ensures that the spring remains neutral at the start of the firing cycle but delivers a modulated reset force only after the firearm has discharged and the action begins to cycle.
In practice, as the bolt carrier group moves rearward following a shot, it strikes the upper arms of the spring, winding the coils and causing the bridged lower arms to press against the trigger. This mechanical shove is calibrated to be strong enough to overcome a relaxed or fatigued finger, yet light enough that a user can still intentionally hold the trigger back if desired. The geometry of the lower bridge is specifically contoured to provide clearance for the disconnector, ensuring the firearm maintains its semi-automatic safety characteristics.
This approach differs from prior solutions by providing a consistent, action-driven reset that does not require the user to change their grip or use a second hand, as is common with bump-fire stocks. By integrating the spring into a modular drop-in assembly or pinning it directly to the receiver, the system provides a more stable and ergonomic way to increase the effective rate of fire while assisting shooters with limited hand mobility.
How does this patent fit in bigger picture?
Technical Landscape
In the early 2010s when ’732 was filed, semi-automatic firearm architectures were typically implemented using mechanical trigger groups that relied on the manual extension of the user's finger to allow a standard trigger spring to return the mechanism to a ready state. At a time when systems commonly relied on the physical clearance of the trigger path by the operator rather than active mechanical assistance from the cycling action, hardware constraints made rapid, repetitive firing non-trivial for users with physiological impairments or fatigue. During this era, the reset phase of a firing cycle was generally treated as a passive recovery step, where the energy of the reciprocating bolt carrier group was utilized for chambering and cocking but was not mechanically coupled to the forward restoration of the trigger interface itself.
Prosecution Position
The disclosed invention represents a technical advancement through an architectural shift that converts the kinetic energy of a firearm's reciprocating bolt carrier group into a positive reset force for the trigger mechanism. By integrating a secondary torsion spring configured to be engaged by the bolt carrier group during its rearward travel, the system overcomes the technical constraint of relying solely on manual finger extension and internal trigger springs for reset. This structural solution achieves the technical effect of actively driving the trigger back to its starting position, thereby enabling a higher sustainable rate of fire and ensuring functional reliability for users with limited extensor capabilities without altering the semi-automatic nature of the firing cycle.
Claims
The patent contains a total of 14 claims, with claims 1, 9, and 13 serving as the independent claims. These independent claims focus on a trigger reset assist mechanism for a firearm, specifically utilizing a torsion spring mounted on a pivot pin that interacts with the bolt carrier group to apply force to the trigger only after the firing cycle has initiated. The dependent claims serve to further define the mechanical properties of the spring, such as specific arm angles and force ranges, while also detailing the timing and distribution of the forces applied to the trigger and bolt carrier group during operation.
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US9021732
- Application Number
- US13831376A
- Filing Date
- Mar 14, 2013
- Publication Date
- May 5, 2015
- External Links
- Slate, USPTO , Google Patents