Heeled Bullet Jacket for Rimfire Accuracy
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Solution Overview
Problem
Rimfire ammunition cartridges with heeled bullets face issues such as the need for external lubrication, potential deformation and expansion of the heel during firing, leading to poor accuracy and potential damage, and inaccuracy due to uneven expanding forces and erosion by hot gases.
Innovation Solution
A heeled bullet encased in a heavy metal jacket, specifically a malleable copper alloy jacket of 0.3 mm to 0.7 mm thickness, which prevents heel deformation and eliminates the need for external lubrication, ensuring a consistent bearing surface and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a heeled bullet is used in rimfire ammunition, then the cartridge can be chambered fully in the barrel allowing different lengths of ammunition to be used, but the heel deforms and expands during firing causing poor gas seal and low accuracy
Solution Approach 1:
The patent applies a copper alloy jacket over the lead core bullet, creating a composite structure. The jacket prevents heel deformation and expansion during firing while the lead core maintains the traditional rimfire bullet properties. This composite construction allows the heeled bullet to maintain dimensional stability and provide consistent gas seal without sacrificing chambering compatibility.
2Ease of operation
If the heel of the bullet is allowed to expand during firing, then it forms part of the bearing surface against the barrel, but uneven expanding forces destabilize the flight trajectory
Solution Approach 1:
The patent changes the physical parameters of the bullet by adding a jacket with specific mechanical properties. The jacket controls the expansion characteristics of the heel during firing, ensuring uniform expansion forces that stabilize the bullet's flight trajectory while still allowing sufficient bearing surface contact with the barrel.
3Object-generated harmful factors
If the exposed portion of the bullet is lubricated with grease or wax, then lead residue build up in the barrel is prevented, but the lubricant is easily contaminated
Solution Approach 1:
The copper alloy jacket serves as a natural lubricant substitute, eliminating the need for external grease or wax applications. The jacket material provides sufficient lubrication properties to prevent lead residue buildup in the barrel while being resistant to contamination from environmental factors.
4Ease of manufacture
If hot gasses erode the base of the bullet, then inconsistencies in the bullet affect its balance and flight path, but the heel may crack or rupture at high firing pressures
Solution Approach 1:
The copper alloy jacket protects the lead core from hot gas erosion and mechanical stress during firing. The jacket acts as a protective barrier that prevents heel cracking and rupture at high firing pressures while maintaining bullet integrity and consistent flight characteristics.
Data Source
AI summary
This invention relates to ammunition. More specifically, this invention is related to rimfire ammunition cartridges with heeled bullets, such as .22 long rifle ammunition cartridges. The invention extends to a heeled bullet for use in such ammunition.