Modular Shotgun Upper Receiver Gas Piston Assembly
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Solution Overview
Problem
Existing firearms, such as the AR-15 and M16, face issues when modified to fire shotgun shells, including jamming and binding due to the direct impingement mechanism hindering proper ejection and cycling of the bolt carrier assembly, and modifications often result in lower receivers that no longer meet military specifications.
Innovation Solution
A modified upper receiver and barrel assembly configured to mount to a mil-spec lower receiver, featuring a bolt carrier group, ejector assembly, and gas piston assembly, which accommodates 2.5 inch long .410 bore shotgun shells, ensuring efficient ejection and proper cycling of the bolt carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the direct impingement mechanism is used in modified AR-15/M16 firearms, then the firearm can be modified to fire shotgun shells, but the mechanism hinders proper ejection and cycling of the bolt carrier assembly
Solution Approach 1:
The firearm system is divided into separate functional modules: a mil-spec lower receiver and a custom upper receiver assembly. The upper receiver contains a dedicated gas-operated piston system that is segmented from the bolt carrier group, allowing independent optimization of gas management and ejection functions. This segmentation enables the shotgun shell firing capability while maintaining reliable cycling through separate gas piston and bolt carrier assemblies.
Solution Approach 2:
A gas piston assembly acts as an intermediary between the barrel and the bolt carrier group. The piston receives gas pressure from fired shotgun shells and transfers this energy to the bolt carrier through a controlled mechanism, mediating the force transmission to ensure proper cycling and ejection. This intermediary piston system prevents direct gas impingement on the bolt carrier, resolving the ejection problems associated with direct impingement.
2Adaptability or versatility
If modifications are made to fire shotgun shells, then the firearm gains versatility, but the lower receivers no longer satisfy military specifications
Solution Approach 1:
The firearm is segmented into two distinct parts: a standard mil-spec lower receiver that maintains military specification compliance, and a custom upper receiver assembly that provides shotgun shell firing capability. This segmentation allows the lower receiver to remain unchanged and meet mil-spec requirements, while the upper receiver is specifically designed for shotgun shells, thus maintaining both versatility and specification compliance simultaneously.
Solution Approach 2:
The upper receiver assembly is designed as a universal adapter that can be mounted to standard mil-spec lower receivers, enabling the combination to fire shotgun shells while the lower receiver itself remains a standard mil-spec component. This multi-functionality approach allows the same mil-spec lower receiver to work with different upper receivers for different calibers or ammunition types, maintaining versatility without compromising the stability of the base platform.
3Productivity
If shotgun shells are fired, then the firearm achieves its intended function, but jamming and binding occur during ejection and extraction
Solution Approach 1:
The gas piston assembly serves as a mediator between the fired shotgun shell and the bolt carrier group, controlling the transfer of gas pressure to ensure smooth operation. The piston system regulates the timing and force of bolt carrier movement, preventing premature or forceful ejection that could cause binding. This intermediary mechanism ensures reliable extraction and ejection of shotgun shells by controlling the cycling process.
Solution Approach 2:
The ejection and extraction components are specifically designed with local quality optimized for shotgun shells. The ejector and extractor mechanisms have geometries and materials tailored to handle the larger, more robust shotgun shell casings compared to rifle cartridges. This localized optimization ensures proper ejection and extraction function specifically for shotgun shells, preventing jamming and binding during these critical operations.
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 enables efficient ejection of fired shotgun shells and proper extraction of the next shell, maintaining military specifications and preventing performance failures like jamming and binding, while allowing the AR-15/M16 to fire .410 bore shotgun shells automatically or semi-automatically.
Implementation Method 1
a gas piston assembly, which accommodates 2.5 inch long .410 bore shotgun shells, ensuring efficient ejection and proper cycling of the bolt carrier
Implementation Method 2
The piston assembly includes a piston, a bonnet, and a biasing member
Data Source
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AI summary
An upper receiver and barrel assembly (200) includes an upper receiver (202), a barrel assembly (204) and a gas piston assembly (206). An upper receiver housing (208) receives a shotgun shell cartridge and the bolt carrier group (211) includes a bolt carrier (218), a bolt (220) within the bolt carrier, a firing pin (222) and an ejector pin (216) to expel fired shells. The barrel assembly includes a barrel (226), a barrel extension (228) and a barrel nut (230) to secure the barrel and barrel extension to the upper receiver housing. The gas piston assembly is configured to coaxially mount about barrel and includes a piston body (280), a piston end cap (294) and a piston bonnet (308) configured to slidably receive the piston end cap therein. A piston gap (332) is defined between the piston end cap and the bonnet end wall. The barrel defines a gas port (336) fluidly connecting the open bore of the barrel with the piston gap. A biasing member (340) urges the piston toward the bonnet.