Firearm Buttstock Cam Lever Adjustment Mechanism
Solution Overview
Problem
Existing firearm buttstocks lack efficient and tool-free mechanisms for adjusting the length and cheek rest height, often requiring complex procedures or prone to unintentional movement during use.
Innovation Solution
The implementation of double-acting spring-biased cam levers that allow for tool-free, single-handed adjustment of both the length of pull and cheek rest height, providing secure locking without interference between cam lever positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nuts and bolts are used to secure and release moving pieces, then the stock becomes very solid with high adjustability, but making adjustments in the field becomes difficult and time consuming
Solution Approach 1:
The patent replaces the traditional nut and bolt mechanical fastening system with a cam lever mechanism. The cam lever uses rotational motion to apply incremental clamping force to secure the adjustment rail, eliminating the need for threaded fasteners. This substitution maintains the solidity and reliability of the connection while dramatically improving ease of operation, allowing field adjustments to be made quickly with a simple lever action rather than requiring tools and multiple steps.
Solution Approach 2:
The cam lever mechanism is designed to be self-contained and self-operating. The user directly manipulates the cam lever to both loosen and tighten the clamping mechanism on the adjustment rail. The system serves itself by using the user's manual input on the lever to automatically generate the necessary clamping force through the cam's geometry, eliminating the need for separate tools or complex assembly procedures.
2Ease of operation
If a threaded jackscrew type mechanism is used, then no tools are required and adjustments can be made, but large adjustments become time consuming and only small movement is allowed between parts
Solution Approach 1:
The cam lever mechanism provides dynamic adjustability where the user can quickly move the adjustment rail over large distances by simply rotating the lever, then lock it in place. Unlike a threaded jackscrew that requires continuous small incremental turns, the cam lever allows for rapid positional changes followed by secure locking. This dynamic operation enables both tool-free adjustment and fast execution of large adjustments, resolving the contradiction between ease of operation and productivity.
Solution Approach 2:
The adjustment mechanism is segmented into two distinct functions: the cam lever provides rapid coarse adjustment capability for large movements, while the indexed notches provide fine adjustment and precise positioning. This segmentation allows the user to quickly make large adjustments with the cam lever action, then lock into specific positions using the notched indexing system, achieving both speed and precision without the time-consuming continuous threading action.
3Ease of operation
If a notched adjustment rod with spring loaded locking button is used, then adjustments are easy to make, but a small amount of movement is allowed between parts
Solution Approach 1:
The patent merges two previously separate mechanisms into one integrated system: the cam lever provides the locking force while the notched adjustment rod provides the positioning references. The cam lever's clamping action secures the adjustment rail to the stock, and the notched rod allows the rail to be positioned at various indexed locations. This combination maintains the ease of operation from the spring-loaded button while significantly improving the security and reliability of the locked position through the cam's strong clamping force.
Solution Approach 2:
The locking mechanism uses a composite approach combining the cam lever's friction-based clamping with the notched rod's geometric locking. The cam lever applies continuous radial pressure through its bearing surface against the adjustment rail, creating high friction that prevents unintended movement. This is combined with the discrete notched positions that guide and limit movement to specific intervals. The composite mechanism achieves both easy adjustment and high security against positional drift.
4Ease of operation
If thumb nuts or bolts are used to clamp the cheek rest, then the design is inexpensive and easy to operate, but the clamping is prone to loosening and moving out of position
Solution Approach 1:
The patent replaces the threaded fastener system (thumb nuts or bolts) with a cam lever mechanism for clamping the cheek rest. The cam lever uses rotational motion to generate incremental clamping force that is applied to the cheek rest assembly. This substitution maintains ease of operation through simple lever action but dramatically improves reliability by providing consistent, tool-free clamping that is resistant to loosening from vibration and recoil, eliminating the problems associated with threaded fasteners that can work loose over time.
5Reliability
If cam levers are used to retain a position, then adjustment is improved, but tools or multi-handed adjustment methods are required to properly set the cam tension
Solution Approach 1:
The cam lever mechanism is designed to be self-adjusting and self-contained. The spring-loaded cam lever automatically maintains proper tension on the adjustment rail through its elastic element. The user simply needs to operate the lever handle to engage or disengage the locking position; the cam mechanism itself self-regulates the clamping force through the spring's elastic properties. This eliminates the need for tools or multi-handed operations to set and maintain cam tension, making the system both reliable and easy to operate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances user convenience and security by enabling easy, precise adjustments without tools, while maintaining the buttstock's position even under recoil or accidental contact.
Implementation Method 1
an opening spring biasing the jaws apart
Implementation Method 2
spring-biased cam levers
Implementation Method 3
The cam lever is rotatable between an open position in which the cam lever is disengaged from the bearing surface, and two closed positions in which the cam lever is engaged with the bearing surface
Data Source
Figure 1
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AI summary
A buttstock includes a mounting extension member attachable to a firearm receiver, an adjustable butt pad for varying the length of the stock, and an adjustable cheek rest for adjusting the height of the stock. The butt pad assembly is attached to the extension member by a laterally compressible clamping member operated by a double-acting cam lever having two locking surfaces and a non-locking release surface. At least one adjustment rail extends forward from the butt pad through opposing movable jaws of the clamping member. The rail can slide forward/rearward to adjust the stock length which is lockable via the cam lever locking surfaces. The cheek rest includes compressible opposing adjustment legs operated by a similarly configured cam lever in one embodiment. The height of the cheek rest may be adjusted and locked in position in a similar manner.