Firearm Trigger Group Reducing Pull Weight via Dual Biasing
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Solution Overview
Problem
Firearms, particularly AR-type weapons, face challenges in achieving a low trigger pull weight while maintaining sufficient hammer force, often resulting in issues like hang fires and undesirable trigger feel due to non-uniformities in the trigger assembly, which can lead to difficulties in precise firing.
Innovation Solution
A firearm trigger group design featuring a trigger and hammer with specific biasing members, including a torsion spring and secondary biasing member, arranged to pivot on defined axes, optimizing the moment arms and forces to reduce trigger pull weight while ensuring adequate hammer force, and sized to fit standard AR-spec lower receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high trigger pull force is used to achieve sufficient hammer force, then reliability of firing is improved, but trigger pull weight increases making precise firing difficult
Solution Approach 1:
The trigger group is divided into separate functional components: a trigger assembly with trigger bar and trigger pivot, and a hammer assembly with hammer pivot. This segmentation allows independent optimization of each component's force requirements and mechanical advantages.
Solution Approach 2:
The system transitions from static force balance to dynamic force management through the sear engagement mechanism. The sear surfaces are designed with specific geometries that create varying mechanical advantages during the trigger pull sequence, allowing light initial pull weight followed by sufficient hammer strike force.
2Force
If internal forces of the trigger group are reduced to achieve lower trigger pull weight, then trigger pull weight is improved, but hammer force becomes insufficient causing hang fires
Solution Approach 1:
The solution moves from one-dimensional force reduction to two-dimensional force optimization by considering both the trigger pull direction and the hammer strike direction. The sear geometry creates different mechanical advantages for these two different dimensional force requirements.
Solution Approach 2:
The moment arm ratios are specifically designed with Rt/Rh < 2 to optimize the force transformation. This parameter change ensures that the trigger pull force is efficiently converted to hammer strike force without requiring excessive trigger pull weight.
3Ease of operation
If sear surfaces are made non-uniform to increase friction, then trigger feel is improved, but positioning precision deteriorates due to washboarding
Solution Approach 1:
The sear surfaces are designed with differentiated local qualities: the primary sear contact surfaces are polished to high precision for smooth engagement and precise positioning, while secondary contact areas may have different surface characteristics to provide tactile feedback without compromising positioning accuracy.
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 design achieves a lighter trigger pull with reduced friction and hang fire risks, improving accuracy and control by optimizing the forces and moments within the trigger group, enhancing the trigger feel and positioning precision.
Implementation Method 1
A hammer biasing member is arranged to bias the hammer in a predetermined rotational direction
Implementation Method 2
A secondary biasing member is also arranged to bias the hammer. The secondary biasing member counteracts the hammer biasing member in the first position, and cooperates with the hammer biasing member in the second position
Data Source
AI summary
In at least one embodiment, a firearm trigger group comprises a trigger arranged to pivot on a trigger axis and a hammer arranged to pivot on a hammer axis. A hammer biasing member is arranged to bias the hammer in a predetermined rotational direction. A secondary biasing member is also arranged to bias the hammer. The hammer is moveable from a first position to a second position upon actuation of the trigger. The secondary biasing member counteracts the hammer biasing member in the first position, and cooperates with the hammer biasing member in the second position.