Bolt Carrier Assembly With Integral Gas Key and Stronger Extraction
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Solution Overview
Problem
Existing bolt carriers and bolts in AR15/M16 firearms suffer from gas leakage due to loose gas keys, cotter pin orientation issues, and structural weaknesses, leading to reliability and maintenance challenges.
Innovation Solution
A bolt carrier assembly with an integral gas key secured by a cross pin, oriented cotter pin, and a fully supported bolt face, along with an extractor that engages a larger portion of the cartridge rim, enhancing structural integrity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate gas key is used and secured with two screws, then the gas key can be attached to the bolt carrier, but the screws become threadedly unsecured due to vibration and heating/cooling cycles, causing gas leakage
Solution Approach 1:
The gas key is integrated directly into the bolt carrier as a single piece, eliminating the separate gas key and screw assembly. This merging of components removes the interface between the gas key and bolt carrier, preventing gas leakage while maintaining attachment reliability.
2Reliability
If the cotter pin is oriented in the prior art manner, then the firing pin can be retained, but the cotter pin bends and breaks due to vibration and heating/cooling cycles, making maintenance difficult
Solution Approach 1:
The bolt carrier is designed with an asymmetric feature that orients the cotter pin in a specific position, ensuring the widest profile of the cotter pin faces the firing pin. This asymmetric orientation prevents the cotter pin from bending or breaking during operation, making maintenance easier when needed.
3Ease of manufacture
If the extractor engages a smaller portion of the cartridge rim, then the extractor structure is simpler, but extraction efficiency is reduced and reliability is compromised
Solution Approach 1:
The extractor is designed with a specific local geometry that increases its engagement with the cartridge rim. The extractor's claw portion is shaped to engage a larger portion of the rim, improving extraction efficiency while maintaining reasonable structural simplicity.
4Ease of manufacture
If the bolt face is not fully supported, then manufacturing is easier, but the lugs become structurally weak and prone to failure
Solution Approach 1:
The bolt is designed with a fully supported bolt face configuration during the manufacturing process, ensuring that all lugs have adequate material support. This preliminary design consideration prevents lug failure while maintaining manufacturing feasibility through standard machining processes.
Data Source
AI summary
An improved bolt and bolt carrier with integral gas key having an extension nozzle threadedly secured and pinned to the gas key for use with a direct gas operated firearm is provided. The extension nozzle is designed to receive a portion of the host firearm's gas operating system. The firing pin retaining pin is oriented so as to expose its widest profile to the firing pin's annular flange, increasing its service life. The bolt has a plurality of lugs extending from its forward end. The extractor recess is constructed so that the face of the bolt is round and the adjacent lugs fully supported. The extractor engages approximately 17% more of a seated ammunition cartridge's rim as compared to the prior art AR15/M16 extractor. The result is an improved bolt and bolt carrier which provides for increased operational reliability.