Two-Stage Trigger Mechanism for Firearm Safety and Consistency
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Solution Overview
Problem
Existing two-stage trigger systems for semi-automatic weapons face safety concerns due to adjustable set screws that can become unsecured, inconsistent trigger pull weights, and lack of secondary safety mechanisms, which can lead to accidental discharges and require costly manufacturing processes.
Innovation Solution
A two-stage trigger mechanism with a non-linear disconnector stop, calibrated disconnector springs, and a secondary safety sear that prevents accidental discharges, eliminating the need for set screws and ensuring consistent trigger pull without manual adjustment, using precision sheet metal fabrication for cost-effectiveness and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If set screws are used to adjust trigger pull weight, then trigger pull weight can be adjusted, but the set screws can become threadedly unsecured after prolonged use leading to uncontrolled discharge or failure to fire
Solution Approach 1:
The patent removes the adjustable set screw mechanism entirely from the trigger assembly. Instead, the trigger pull weight is determined by the inherent spring tension of the disconnector spring, which is selected during manufacturing to provide the desired trigger pull weight. This eliminates the reliability issue of set screws becoming unsecured while maintaining the ability to adjust trigger pull weight through spring selection.
Solution Approach 2:
The patent changes the parameter of trigger pull weight adjustment from a field-adjustable mechanism (set screws) to a manufacturing-stage parameter (spring tension selection). Different disconnector springs with different tensions are used to achieve different trigger pull weights, and the appropriate spring is selected based on the desired trigger characteristics.
2Ease of manufacture
If flat surface to surface contact is used between disconnector and trigger, then manufacturing is simplified, but any deviation from perfect component size causes poor sear engagement and inconsistent trigger pull weight
Solution Approach 1:
The patent replaces the flat surface contact between the disconnector and trigger with a curved surface contact. Specifically, the disconnector has a curved surface that contacts a corresponding curved surface on the trigger, creating a line contact rather than a surface-to-surface contact. This curvature compensates for manufacturing tolerances and ensures consistent trigger pull weight across production batches.
3Ease of operation
If light weight trigger is used to reduce force necessary to discharge firearm, then accuracy is improved by reducing mechanical distractions, but safety concerns arise from potential for accidental or negligent discharges
Solution Approach 1:
The patent divides the trigger pull into two distinct stages: first stage for safety and second stage for firing. The first stage involves pulling the trigger to the point where the disconnector releases the hammer, but the second stage requires additional trigger travel to actually discharge the firearm. This segmentation allows for a lighter overall trigger weight while maintaining safety through the two-stage mechanism.
Solution Approach 2:
The patent implements a preliminary safety action in the first stage of the trigger pull. The shooter must first complete the first stage trigger pull to cock the hammer and prepare the firearm for discharge, but the actual firing is prevented until the second stage is completed. This preliminary action ensures intentional discharge while allowing for a lighter trigger overall.
4Reliability
If secondary safety sear is added to prevent accidental discharge, then safety is improved, but device complexity increases
Solution Approach 1:
The patent merges the secondary safety sear function with the existing disconnector component. Rather than adding a completely separate safety mechanism, the disconnector is designed to perform both its primary function of controlling the two-stage trigger pull and the secondary function of acting as a safety sear that prevents accidental discharge. This integration maintains safety while minimizing additional complexity.
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 significantly reduces the risk of accidental discharges while providing consistent and reliable trigger performance, shot-to-shot accuracy, and cost-effective manufacturing, ensuring user safety and precision without the need for manual fitting or adjustment.
Implementation Method 1
spring loaded disconnector assembly (27) having a disconnector (26) and a calibrated disconnector spring (28)
Implementation Method 2
a spring loaded hammer (24) having an overlapping hammer sear hook (23)
Data Source
AI summary
A two-stage trigger assembly for the M16 or AR15 weapon systems. The trigger assembly comprises a spring loaded hammer, trigger and disconnector. Calibrated springs are provided to facilitate the adjustment of the second stage trigger pull weight. No set screws adjustments are necessary and a secondary safety sear similar to the factory original fire control components has been incorporated to prevent the unintentional mechanical discharge of the firearm. Installation of the disclosed device is identical to the factory fire control group and requires no hand fitting.