Segmented Lead-Free Bullet Core for Swaging Stability

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Solution Overview

Problem

Existing lead-free bullets face challenges in maintaining ballistic stability and accuracy due to the hardness of non-toxic metals, which makes mechanical swaging processes ineffective, resulting in gaps between the jacket and core and subsequent distortion when fired.

Innovation Solution

A bullet design featuring a mid core and rear core in tandem alignment, where the mid core is harder than the rear core, with a jacket enveloping both, and the rear core having a Brinell hardness less than 50, allowing for effective mechanical swaging and proper boat-tail formation to prevent propellant gas entry and maintain stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If non-toxic metals are used to replace lead in bullet cores, then environmental toxicity is reduced, but the hardness of the metal increases making mechanical swaging ineffective

Engineering Contradiction:

Improveenvironmental toxicityVSAvoidmechanical swaging effectiveness

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The bullet core is divided into two distinct segments: a front core made of hard non-toxic metal (tungsten, tungsten carbide, or ferro-tungsten) for penetration, and a rear core made of soft non-toxic metal (tin, zinc, aluminum, iron, copper, or bismuth) for swaging. This segmentation allows each segment to fulfill its specific functional requirement independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the bullet core have different material properties optimized for their specific functions. The front core has high hardness and density for penetration, while the rear core has low hardness for deformability during swaging. This local differentiation of material properties resolves the contradiction between hardness and manufacturability.

Inventive Principle:

Principle #3Local quality

2Strength

If the core material is made harder to maintain structural integrity, then penetration capability is improved, but the mechanical swaging process becomes ineffective creating gaps between jacket and core

Engineering Contradiction:

Improvestructural integrityVSAvoidjacket-core interface fit

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The core is segmented into front and rear portions with different hardness characteristics. The front core maintains high hardness for structural integrity and penetration, while the rear core provides softness for proper jacket engagement during swaging, eliminating gaps at the interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bullet core exhibits local quality variation where the front core has high hardness for strength and penetration, while the rear core has low hardness for manufacturability. This spatial differentiation of material properties simultaneously achieves both structural integrity and manufacturing precision.

Inventive Principle:

Principle #3Local quality

3Strength

If a single hard non-toxic metal is used for the entire core, then penetration is improved, but boat-tail formation becomes difficult resulting in jacket distortion during firing

Engineering Contradiction:

Improvepenetration capabilityVSAvoidboat-tail formation

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The core is divided into front and rear sections with different material properties. The front core provides the hardness needed for penetration, while the rear core's softness enables proper boat-tail formation through mechanical swaging, preventing jacket distortion during firing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the core have locally optimized material properties: the front core is hard for penetration capability, while the rear core is soft for boat-tail formation. This local differentiation resolves the contradiction between penetration strength and ease of boat-tail manufacture.

Inventive Principle:

Principle #3Local quality

4Ease of manufacture

If lead is used in the bullet core, then manufacturability and cost are optimized, but environmental toxicity increases

Engineering Contradiction:

ImprovemanufacturabilityVSAvoidenvironmental toxicity

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The bullet core uses a composite structure with multiple non-toxic metals (front core of tungsten/tungsten carbide/ferro-tungsten and rear core of tin/zinc/aluminum/iron/copper/bismuth) that together replicate the desirable manufacturing properties of lead while eliminating its toxicity. This composite approach achieves both ease of manufacture and environmental safety.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS20110088537A1Jacketed boat-tail bullet

Publication Date: 2011.04.21 OLIN CORP

AI summary

A bullet includes at least a mid core and a rear core in tandem alignment. The hardness of the mid core is greater than the hardness of the rear core. A jacket envelops both the mid core and the rear core. The jacket has a generally cylindrical sidewall, which is in contact with the mid core, and a boat-tail, which is in contact with the rear core. The rear core is substantially contained within the boat-tail. The mid core and the rear core may be substantially lead-free. In one embodiment, the bullet includes a front core in tandem alignment with the rear core and in contact with a nose portion of the jacket. In another embodiment, the mid core extends from the nose portion of the bullet to the boat-tail.