Bolt Action Rifle Bolt with Reduced Middle Section
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Solution Overview
Problem
Bolt action rifles with two or three locking lugs are not conducive to feeding cartridges from double stack magazines, such as those used in AR-15 style rifles, due to geometric limitations that prevent the bolt from extending far enough to reliably strip cartridges, especially when the action is cycled.
Innovation Solution
A bolt design with a reduced diameter middle section and specially angled surfaces allows full rotation between locked and unlocked positions, providing clearance between the bolt body and magazine feed lips, enabling the use of double stack magazines by maintaining a substantially full diameter in the front and rear sections for support and aesthetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bolt body has a substantially full diameter throughout its length, then the bolt provides adequate structural support and maintains proper engagement with locking lugs, but the bolt cannot rotate fully between locked and unlocked positions when in battery with the chamber due to interference with magazine feed lips
Solution Approach 1:
The bolt body is divided into three distinct sections: a front section with substantially full diameter for structural support and locking lug engagement, a middle section with reduced diameter to clear magazine feed lips during rotation, and a rear section with substantially full diameter for structural support. This segmentation allows each section to serve its specific function without interfering with others.
Solution Approach 2:
The middle section of the bolt body has a reduced diameter specifically where it would otherwise interfere with magazine feed lips during rotation. This localized modification provides the necessary clearance for full rotation while maintaining full diameter in the front and rear sections where structural strength is critical.
2Ease of operation
If the bolt body diameter is reduced in the middle section to allow full rotation, then the bolt can rotate freely between locked and unlocked positions, but the bolt may lack adequate structural support and engagement capability
Solution Approach 1:
The bolt body is divided into three distinct sections: a front section with substantially full diameter for structural support and locking lug engagement, a middle section with reduced diameter to clear magazine feed lips during rotation, and a rear section with substantially full diameter for structural support. This segmentation allows each section to serve its specific function without interfering with others.
Solution Approach 2:
The middle section of the bolt body has a reduced diameter specifically where it would otherwise interfere with magazine feed lips during rotation. This localized modification provides the necessary clearance for full rotation while maintaining full diameter in the front and rear sections where structural strength is critical.
3Reliability
If the bolt is designed with two or three locking lugs in conventional positions, then the bolt provides reliable locked breech engagement, but the bolt geometry prevents reliable cartridge stripping from double stack magazines
Solution Approach 1:
The bolt body is divided into three distinct sections: a front section with substantially full diameter for structural support and locking lug engagement, a middle section with reduced diameter to clear magazine feed lips during rotation, and a rear section with substantially full diameter for structural support. This segmentation allows each section to serve its specific function without interfering with others.
Solution Approach 2:
The middle section of the bolt body has a reduced diameter specifically where it would otherwise interfere with magazine feed lips during rotation. This localized modification provides the necessary clearance for full rotation while maintaining full diameter in the front and rear sections where structural strength is critical.
Data Source
AI summary
A bolt for a bolt-action firearm in one embodiment is movably disposed in a receiver between forward closed breech and rearward open breech axial positions. The bolt includes an operating handle and plurality of bolt lugs arranged to selectively engage locking lugs in the firearm. The bolt is rotatable between locked and unlocked breech positions when in the closed breech position. The bolt body has a dimensionally reduced middle section with unique configuration adapted to allow the bolt to rotate when closed without interference from the magazine feed lips. Using this design, the bolt may include three bolt lugs in one embodiment for secure lockup and minimal angular rotation between the locked and unlocked breech positions. The bolt is usable with both single and double stack box type magazines with one of the bolt lugs operating to reliably strip cartridges from either type magazine.