Elastomeric Extractor Biasing Member for Firearm Bolt Assembly
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Solution Overview
Problem
Conventional pivoting extractor systems in firearms experience premature failure due to repeated stresses, high heat, and vibrations, leading to inconsistent biasing force from metal springs.
Innovation Solution
An elastomeric biasing member with a specific geometry is used to provide controlled and constant tension to the pivoting extractor, replacing traditional metal springs, ensuring consistent performance throughout the extractor's range of motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal spring is used to provide biasing force to the extractor, then the extractor can be biased into engagement with the cartridge, but the spring is subjected to repeated stresses, high heat, and vibration causing premature failure
Solution Approach 1:
The patent changes the material parameter from metal to elastomeric polymer, which fundamentally alters the mechanical properties. The elastomeric material provides the necessary biasing force while being resistant to heat and vibration, thereby extending service life and improving reliability under extreme conditions.
Solution Approach 2:
The biasing member is formed from elastomeric material that can be considered a composite or at least a fundamentally different material class from traditional metal springs. This material substitution provides both the required mechanical function and enhanced durability against environmental degradation.
2Reliability
If a metal spring is used to bias the extractor, then the extractor can engage the cartridge, but the biasing force becomes inconsistent under repeated compression and relaxation cycles
Solution Approach 1:
The elastomeric material exhibits different mechanical behavior compared to metal springs. It maintains more consistent elastic properties through repeated compression cycles and is less susceptible to fatigue, heat-induced property changes, and vibration damage, thereby providing more stable and predictable biasing force.
3Force
If a coiled metallic spring is used to provide biasing force, then the extractor can be urged into engagement, but the spring undergoes compression and relaxation cycles while exposed to heating and cooling cycles leading to premature failure
Solution Approach 1:
The elastomeric material provides the necessary force while being inherently more resistant to thermal cycling and vibration. The material's viscoelastic properties allow it to maintain force output without undergoing the same degradation mechanisms that affect metal springs under repeated thermal and mechanical stress.
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 elastomeric biasing member maintains a consistent extractor tension, reducing the risk of premature failure and providing reliable operation across various firearm types, including semi-automatic and fully automatic systems.
Implementation Method 1
The body of the biasing member can further consist essentially of an elastomeric material
Data Source
AI summary
A biasing member for a bolt assembly of a firearm is described herein. The biasing member comprises a body having a first portion configured to engage and seat within a biasing member receiving indentation of an arm of the extractor, and a second portion configured to engage and seat within a receiving area along a bolt of the firearm. The body provides a biasing force directed against the extractor arm. The body comprises an elastomeric material, and is configured such that the first and second portions provide varying levels of compression sufficient to maintain a substantially constant extractor tension between the extractor arm and a cartridge.