Semiautomatic Trigger Reset Mechanism for MP5 Drop-In Retrofit
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Solution Overview
Problem
Existing semiautomatic firearm trigger mechanisms are not readily adaptable to firearm platforms other than the AR-pattern, particularly the Heckler & Koch MP5 platform, limiting the ability to increase the rate of fire without requiring modifications to the bolt carrier or fire control mechanism.
Innovation Solution
A semiautomatic trigger mechanism that can be retrofitted into MP5-pattern firearms, featuring a 'drop-in' replacement trigger module with a three-position safety selector, utilizing a pivoting ejector to actuate the locking member and force the trigger to reset, rather than relying on bolt carrier contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a forced reset trigger mechanism is implemented to increase rate of fire, then productivity increases, but device complexity increases and adaptability to different firearm platforms decreases
Solution Approach 1:
The trigger mechanism is divided into separate functional components: a trigger member, a disconnector, a locking member, and a cam member. Each component performs a specific function, allowing the complex forced reset mechanism to be broken down into manageable, independently analyzable parts that can be manufactured and assembled separately.
Solution Approach 2:
The cam member is designed to rotate dynamically during the cycling of the action, transitioning between different positions to either force the trigger member to the set position or allow normal operation. This dynamic behavior enables the mechanism to adapt its function based on the operational mode selected.
2Productivity
If a forced reset trigger mechanism is implemented to increase rate of fire, then productivity increases, but adaptability to different firearm platforms decreases
Solution Approach 1:
The trigger mechanism is designed with universal mounting features and standardized interface points that can accommodate different firearm platforms. The mechanism can function in multiple modes (normal semi-automatic, forced reset, and three-position safety) making it adaptable to various application requirements across different firearm types.
Solution Approach 2:
The mechanism includes adjustable parameters such as cam rotation timing and locking member positioning that can be modified to suit different firearm platforms and operational requirements. The three-position safety selector provides discrete parameter changes in the operational mode.
3Ease of manufacture
If rigid mechanical contact between bolt and trigger member is used to force reset, then ease of manufacture improves, but device complexity increases and adaptability decreases
Solution Approach 1:
The cam member acts as an intermediary between the cycling action and the trigger member. Instead of direct rigid contact between the bolt and trigger, the cam member translates the cyclic motion into controlled rotational movement that forces the trigger to the set position. This intermediary mechanism provides more controlled and predictable operation.
Solution Approach 2:
The cam member utilizes curved surfaces and rotational geometry to transfer motion from the linear cycling action to the angular movement of the trigger member. This curved mechanical advantage provides smooth, controlled forcing of the trigger to the set position rather than abrupt rigid contact.
Data Source
AI summary
A trigger mechanism having a hammer, a trigger member, movable ejector lever, and locking member. The trigger member being forced to the set position by the hammer during rearward pivoting. A locking member is adapted to move between a first position at which the locking member mechanically blocks the trigger member from moving to the released position and a second position at which the locking member does not mechanically block the trigger member allowing the trigger member to be moved to the released position. The locking member is spring biased toward the first position and moved against the spring bias to the second position by contact from the movable ejector lever during forward movement of the bolt carrier as the bolt carrier reaches a substantially in-battery position.