Firearm Bolt Head Centering Ramps for Acentric Movement
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Solution Overview
Problem
Existing bolt heads in firearms suffer from acentric movement during the locking process, leading to premature wear, material fatigue, and potential jams, especially during automatic firing.
Innovation Solution
The bolt head design incorporates centering ramps that extend obliquely toward the rear, aiding in self-centering during the locking process, and a cam pin with a stepped taper for improved torque absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bolt head moves forward into the locking space during the locking process, then the locking function is achieved, but acentric movement occurs leading to premature wear and material fatigue
Solution Approach 1:
The centering ramps are designed to perform the centering action before the bolt head fully engages the locking space. The oblique surfaces of the centering ramps make contact with the locking sleeve earlier in the movement sequence, guiding the bolt head into proper alignment before the locking lugs engage, thereby preventing acentric movement and reducing wear.
Solution Approach 2:
The centering ramps act as an intermediary element between the bolt head and the locking space. These ramps provide a mediating surface that gradually guides the bolt head into correct positioning, preventing direct impact and acentric engagement between the bolt head and the locking lugs.
2Manufacturing precision
If locking lugs with sharp edges are used, then manufacturing precision is improved, but impacting and striking occurs during acentric movement causing jams
Solution Approach 1:
The centering ramps perform the alignment function before the locking lugs with sharp edges engage the locking space. This preliminary centering action ensures that the sharp-edged locking lugs approach the locking surfaces in proper alignment, preventing impacting and striking that would otherwise occur during acentric movement.
Solution Approach 2:
The centering ramps provide a cushioning effect before the locking lugs engage. The oblique surfaces of the ramps gradually guide the bolt head into position, cushioning against sudden impacts and preventing the sharp edges of the locking lugs from striking the locking surfaces during acentric movement.
3Ease of operation
If clearance is provided between movably mounted parts, then ease of operation is improved, but acentric movement and oscillations occur reducing reliability
Solution Approach 1:
The centering ramps are provided at specific locations on the bolt head where guidance is needed, rather than requiring tight clearance throughout the entire bolt head assembly. This localized feature provides centring guidance precisely where the bolt head contacts the locking space, maintaining reliability while preserving the necessary clearance for overall movability.
Solution Approach 2:
The centering ramps serve as intermediary guidance features that work within the existing clearance between the bolt head and locking space. Rather than eliminating clearance, the ramps mediate the interaction by providing positive guidance surfaces that prevent acentric movement despite the presence of necessary clearance for operation.
Data Source
AI summary
Firearms and bolt carriers having a bolt head including a bolt head axis and a plurality of locking lugs, wherein at least two recesses having a radius, measured with respect to the bolt head axis, are formed on the bolt head between at least two adjacent locking lugs. To improve the guidance of the bolt head, at least two centering ramps, which are designed obliquely to the bolt head axis and protrude in the axial direction toward the rear up to a central radius that is greater than the radius, for self-centering the bolt head during the bolt process are formed in the region of the recesses.