Firearm Stock Lever Arm Anti-Rattle Mechanism
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Solution Overview
Problem
Collapsible firearm stocks experience unacceptable movement and rattle due to manufacturing tolerance variations, leading to stability and accuracy issues, and existing anti-rattle solutions are either expensive or unsuitable for retail consumers.
Innovation Solution
A stock with a length of pull adjustment mechanism featuring a locating member and lever arms that engage with the firearm's receiver extension to limit movement, using a biased configuration to secure the stock in place without additional costly components, allowing for adjustable length and reduced friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional anti-rattle mechanisms (springs, buffer tube holders) are used, then movement and rattle are reduced, but manufacturing cost increases and device complexity increases
Solution Approach 1:
The patent removes the buffer tube holder component entirely and uses only the receiver extension's built-in features (recesses and flanges) to provide anti-rattle functionality. This extraction of unnecessary components reduces device complexity while maintaining the anti-rattle performance through the lever arm mechanism that engages with the receiver extension's existing structure.
Solution Approach 2:
The receiver extension is designed to serve multiple functions: it provides the structural connection between the stock and firearm, includes built-in recesses and flanges for positioning, and incorporates the anti-rattle mechanism through its own features rather than requiring separate components. This multi-functionality reduces the overall number of parts needed in the system.
2Reliability
If traditional anti-rattle mechanisms (springs, buffer tube holders) are used, then movement and rattle are reduced, but manufacturing cost increases
Solution Approach 1:
The patent eliminates the buffer tube holder component that would require additional manufacturing processes and assembly steps. By using only the receiver extension's built-in features and the lever arm mechanism, the manufacturing cost is reduced while maintaining anti-rattle performance through a simpler assembly process.
Solution Approach 2:
The lever arm mechanism uses simple, inexpensive components (lever arm, locating member, spring) that are easier and cheaper to manufacture than traditional anti-rattle mechanisms. These components are designed to be cost-effective for retail consumers while providing sufficient anti-rattle functionality.
3Reliability
If flaps are used to prevent movement, then anti-rattle feature is provided, but friction increases and movement becomes unsmooth
Solution Approach 1:
The lever arm mechanism transitions from a static flap design to a dynamic system where the lever arm can pivot between engaged and disengaged positions. This dynamic design allows the locating member to engage with the receiver extension's recesses for anti-rattle performance while allowing smooth movement when the lever arm pivots to the disengaged position, eliminating the friction problem of fixed flaps.
4Reliability
If flaps are used to prevent movement, then anti-rattle feature is provided, but the flaps creep and loosen over time
Solution Approach 1:
The lever arm mechanism provides a more durable anti-rattle solution than fixed flaps because the lever arm can be positively engaged with the receiver extension's recesses through the locating member. This engagement mechanism prevents the creep and loosening that occurs with flaps, as the lever arm's engagement position is maintained by the mechanical interlocking of the locating member with the recesses rather than relying on friction or deformation.
Data Source
AI summary
A stock for a firearm is disclosed. The stock has a length of pull (LOP) adjustment mechanism. The LOP adjustment mechanism is biased towards an engaged configuration and is movable to a disengaged configuration. A locating member protrudes into a stock mounting space and a first arm is in an engagement position when the LOP adjustment mechanism is in the engaged configuration. The locating member is translated such that the locating member does not protrude into the mounting space and the first arm is pivoted into a disengagement position when the LOP adjustment mechanism is in the disengaged configuration.