Firearm Bolt Assembly Pin Retainer Design
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Solution Overview
Problem
Existing bolt assemblies for firearms lack an effective means to retain the pin within the assembly, leading to potential loss or damage of the pin, which can render the firearm unreliable.
Innovation Solution
The bolt assembly incorporates a retainer, such as a circlip or a P-shaped retainer, positioned inward relative to the exterior surface of the bolt assembly, which is removably coupled to the pin to securely retain it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no retainer is used to hold the pin, then the bolt assembly structure is simpler, but the pin may fall out or be lost leading to firearm unreliability
Solution Approach 1:
A retainer component is introduced as an intermediary element between the pin and the bolt assembly. The retainer has a curved portion that extends around the pin and a straight portion that engages with the extractor, mediating the retention function and preventing pin displacement without requiring complex structural modifications to the pin or bolt itself.
Solution Approach 2:
The retainer is positioned inward relative to the exterior surface of the bolt assembly, with the curved portion nesting around the pin and the straight portion nesting within the extractor slot. This nested configuration allows the retainer to function within the existing bolt assembly geometry without adding external protrusions or increasing overall device complexity.
2Reliability
If the pin is retained inward relative to the exterior surface, then the pin is securely held, but the manufacturing and assembly process becomes more complex
Solution Approach 1:
The retainer is pre-positioned within the bolt assembly before the pin is fully installed. The curved portion of the retainer is already in place to receive and hold the pin, and the straight portion is positioned to engage with the extractor slot. This preliminary action simplifies the final assembly step where the pin is simply inserted into the pre-configured retainer rather than requiring complex simultaneous alignment of multiple components.
3Strength
If the retainer extends further outward, then the pin retention is stronger, but the device complexity and potential interference with other components increases
Solution Approach 1:
The retainer applies retention force locally at critical points rather than uniformly across its entire length. The curved portion provides local retention at the pin interface, while the straight portion provides local engagement with the extractor slot. This localized quality approach achieves strong pin retention without requiring the retainer to extend outward uniformly, thereby reducing device complexity and potential interference with other components.
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 retainer effectively prevents the pin from moving laterally or falling out, even if the biasing member fails, ensuring the firearm remains reliable and allowing for increased axial stroke length of the bolt assembly.
Implementation Method 1
the retainer is configured to exert a radial force on the extractor relative to an axis defined by the pin
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A bolt assembly (200) that includes a bolt (210) defining at least one bolt opening (213) and an extractor (220) that is configured to pivot relative to the bolt (210). The extractor (220) may define at least one extractor opening (223). The bolt assembly (200) may include a pin (230) positioned within the at least one bolt opening (213) and the at least one extractor opening (223). The bolt assembly (200) may include a retainer (240) that is positioned inward relative to an exterior surface of the bolt assembly (200). The retainer (240) may be removably coupled to the pin (230).