Firearm Breech Cover Interlock for Bullpup Safety
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Solution Overview
Problem
Bullpup configuration firearms face challenges in preventing accidental discharge when the breech cover is open, as fire control disconnection is impractical due to the remote location of the fire control group, necessitating a mechanical interlock to prevent the action from returning to battery.
Innovation Solution
An interlock mechanism that coordinates the motion of the breech cover assembly with the fore end of the firearm, using a latch and action bar system with complementary hooks and a spring bias, to prevent the breech cover from opening while the firearm is in battery, and allowing access when the firearm is out of battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a reciprocable cover is provided over the breech to allow access for clearing malfunctions, then ease of operation is improved, but the risk of accidental discharge increases when the cover is open
Solution Approach 1:
An interlock mechanism acts as an intermediary between the breech cover assembly and the action bar, preventing the action from returning to battery when the cover is open. The interlock includes a latch on the cover assembly and a catch on the action bar that engage to block battery position, thereby mediating the interaction between cover position and firing capability
2Volume of moving object
If the fire control group is placed remotely from the cover (bullpup configuration), then compactness is improved, but the ability to disconnect fire control when cover is open becomes impractical
Solution Approach 1:
The patent replaces the conventional fire control disconnection mechanism with a mechanical interlock system that directly couples the breech cover position to the action bar movement. This mechanical substitution eliminates the need for complex fire control group disconnection while maintaining the bullpup compact configuration
3Object-affected harmful factors
If a mechanical interlock is added to prevent action from returning to battery when cover is open, then safety is improved, but device complexity increases
Solution Approach 1:
The interlock mechanism is segmented into distinct functional components: a latch mounted on the breech cover assembly, a catch on the action bar, and a spring for providing engagement force. This segmentation allows each component to be simple in design while collectively achieving the safety function
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 interlock effectively prevents accidental discharge by ensuring the breech cover remains closed when the firearm is ready to fire and allows safe access to the breech for maintenance by disengaging when the firearm is out of battery, enhancing operational safety and usability.
Implementation Method 1
the latch may further comprise a spring biasing the latch into engagement with the catch
Data Source
AI summary
A breech cover interlock coordinates the motion of a breech cover with the motion of the fore end of a pump action firearm. The interlock features an action bar which is connected to the fore end and has a catch which is engaged by a latch mounted with the cover on a movable buttstock. Engagement between the catch and the latch prevents the buttstock and cover from moving and thereby exposing the firearm's breech while the firearm's action is in battery as evidenced by the position of the fore end. Motion of the fore end out of battery disengages the latch and catch and permits the cover to be moved out of overlying position with the breech to permit access to the breech to clear a malfunction.