Hinged Firearm Receiver Integrating Folding Stock
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Solution Overview
Problem
AR-pattern rifles lack a folding stock feature that does not compromise the firearm's cycle rate, length, or weight, as existing solutions either increase length and weight or require non-standard buffer extensions, affecting recoil system reliability.
Innovation Solution
A firearm receiver with an integrated hinge that allows the rear receiver body to fold, compatible with a standard buffer tube and spring, shifting recoil force management from the lower to the upper receiver, enabling a lighter and more compact folding stock without requiring a buffer extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a folding stock feature is integrated into the lower receiver, then the rifle can fold its stock for compact storage, but the length and weight of the rifle increase
Solution Approach 1:
The receiver is divided into two separate parts: an upper receiver and a lower receiver. The folding stock mechanism is integrated into the lower receiver, which can be detached from the upper receiver. This segmentation allows the folding stock feature to be isolated in a removable component, reducing the overall length when the lower receiver is detached for storage or transport.
Solution Approach 2:
The lower receiver is designed with a hinge mechanism that allows it to fold relative to the upper receiver. This dynamic configuration enables the stock to transition between extended (for firing) and folded (for storage) positions, providing adaptability without permanently increasing the rifle's length.
2Adaptability or versatility
If a folding stock feature is integrated into the lower receiver, then the rifle can fold its stock for compact storage, but the weight of the rifle increases
Solution Approach 1:
By separating the folding stock mechanism into the detachable lower receiver, the weight penalty is confined to a removable component. When the lower receiver is detached for storage, the overall weight of the stored configuration is reduced, while the full weight is available when assembled for use.
Solution Approach 2:
The lower receiver is designed with specific local properties (hinge mechanism, folding geometry) only where needed for the folding function. The rest of the receiver maintains standard AR-15 construction, minimizing unnecessary weight addition while achieving the folding capability.
3Adaptability or versatility
If a buffer extension is used to enable folding stock, then the folding feature is achieved, but the recoil system reliability is affected
Solution Approach 1:
The folding stock mechanism is extracted from the traditional buffer tube assembly and integrated into the lower receiver itself. This extraction eliminates the need for a buffer extension, allowing the use of a standard buffer and spring that maintain the original recoil system specifications and reliability characteristics.
Solution Approach 2:
Instead of adding a buffer extension to the buffer tube to achieve folding (as in prior art), this invention inverts the approach by integrating the hinge mechanism directly into the lower receiver. This reversal allows the buffer system to remain standard and unchanged, preserving reliability while achieving the same folding functionality.
4Weight of moving object
If the lower receiver is made slimmer and lighter, then material savings are achieved, but the recoil force management becomes more challenging
Solution Approach 1:
The receiver segmentation allows the lower receiver to be optimized independently for weight reduction. The hinge mechanism is designed to handle recoil forces through its pivot connection to the upper receiver, enabling the lower receiver to be made lighter while maintaining adequate force management through the hinge joint design.
Data Source
AI summary
Provided is a hinged firearm receiver configured to operate with an AR-pattern Bolt carrier group, buffer, buffer spring, and buffer tube. The firearm upper receiver has an integral hinge that connects to a rear receiver body and provides an AR-pattern firearm the ability to have a folding stock to reduce length for storage or transportation purposes.