Polymer Cartridge Casing With Metal Sleeve for Consistent Subsonic Firing

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Solution Overview

Problem

Conventional ammunition casings made of brass are heavy, expensive, and can cause uneven pressure buildup leading to inaccurate bullet performance, while alternative materials face issues like jamming and fouling in subsonic rounds.

Innovation Solution

A high-strength polymer-based cartridge casing with a metal insert, featuring a thickened sleeve section and uniform neck expansion, designed to withstand firing pressures and ensure consistent bullet release, suitable for both standard and subsonic ammunition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If brass cartridge cases are used, then strength and reliability are improved, but weight and cost increase

Engineering Contradiction:

Improvecartridge case strengthVSAvoidcartridge weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent changes the material parameter from traditional brass to polymer, fundamentally altering the weight-to-strength ratio. The polymer material provides sufficient strength for subsonic ammunition while significantly reducing weight, directly resolving the contradiction between strength and weight.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cartridge case uses a composite structure combining polymer material with metal inserts (such as steel or brass) at critical stress points. This composite approach maintains overall weight reduction while providing metallic strength where needed, balancing the contradiction between lightweight design and structural strength.

Inventive Principle:

Principle #40Composite materials

2Strength

If brass cartridge cases are used, then strength and reliability are improved, but cost increases

Engineering Contradiction:

Improvecartridge case strengthVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from expensive brass to more economical polymer material, directly reducing manufacturing cost while maintaining adequate strength through proper material selection and structural design.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The polymer cartridge cases are designed as disposable ammunition components that are inexpensive to manufacture and replace. This approach prioritizes low cost and ease of manufacture, with the polymer material providing sufficient performance for the intended application without requiring expensive recovery or recycling processes.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If conventional cartridge designs are used, then manufacturing simplicity is maintained, but pressure distribution uniformity deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidpressure distribution uniformity

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a neck expansion feature at a specific location in the cartridge case. This localized geometric modification ensures uniform pressure distribution during firing while maintaining overall manufacturing simplicity, as only a specific region requires the expanded neck design rather than complete redesign of the entire case structure.

Inventive Principle:

Principle #3Local quality

4Weight of moving object

If polymer cartridge cases are used, then weight is reduced, but strength and reliability may deteriorate

Engineering Contradiction:

Improvecartridge weightVSAvoidcartridge reliability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12410994B2Polymer-based cartridge casing for subsonic ammunition

Publication Date: 2025.09.09 PCP TACTICAL LLC

AI summary

A high strength polymer-based blank cartridge having a first end; a shoulder disposed approximate the first end; a second end opposite the first end; and an insert engaged to the second end. A metal sleeve extends between the shoulder and insert, and a polymer sheath covers at least the metal sleeve. A propellant chamber is formed between the shoulder and the insert by at least the metal sleeve, and the propellant chamber has an unobstructed and a reduced volume, wherein the reduced volume is reduced in comparison to a propellant chamber of a standard cartridge.