Polymer Ammunition with Metal Injection Molded Primer Insert

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Solution Overview

Problem

Conventional plastic ammunition cartridge casings fail to provide reliable and consistent ballistic performance due to issues such as insufficient bullet pull, non-uniform chamber pressure, and structural integrity, leading to potential weapon jams or damage.

Innovation Solution

A molded primer insert made from metal, alloy, or ceramic, specifically stainless steel, with a ductile polymer overmolding, including a primer flash hole and flange, is used to create a robust and uniform polymeric ammunition cartridge, ensuring consistent bullet seating and pressure within the casing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If conventional plastic cartridge casings are used, then weight is reduced and cost is lowered, but reliability and structural integrity deteriorate

Engineering Contradiction:

Improvecartridge casing weightVSAvoidcartridge reliability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The cartridge casing combines polymer material for the main body with a metal injection molded primer insert. The polymer provides lightweight properties while the metal insert provides structural strength and reliability at the critical primer location, creating a composite structure that achieves both weight reduction and reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The primer insert is specifically placed at the base of the cartridge where high strength and precision are needed for primer seating and firing pin impact resistance. This localized reinforcement with metal material provides the necessary reliability without making the entire cartridge heavy, as only the critical area is strengthened.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If polymer cartridge casings are used, then manufacturing cost is reduced, but manufacturing precision and uniformity deteriorate

Engineering Contradiction:

Improvemanufacturing costVSAvoidbullet seating uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The metal injection molded primer insert provides precise dimensional control and uniformity for primer seating, while the polymer body can be cost-effectively manufactured. The combination allows the precision-critical primer area to be made with high-precision metal molding while the less critical body portions use cost-effective polymer manufacturing.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The metal injection molding process replaces traditional mechanical assembly of the primer assembly with a single integrated molded component. This substitution provides better dimensional consistency and uniformity in primer seating depth and orientation, eliminating variations introduced by separate assembly operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Weight of moving object

If polymer cartridge casings are used, then weight is reduced, but bullet pull consistency and chamber pressure uniformity deteriorate

Engineering Contradiction:

Improvecartridge casing weightVSAvoidchamber pressure uniformity

Core Design Contradiction:

Weight of moving objectVSManufacturing precision

Solution Approach 1:

The metal primer insert provides consistent and uniform primer seating depth and orientation, which ensures uniform ignition and consistent chamber pressure generation. The polymer body maintains lightweight properties while the metal insert ensures pressure uniformity through precise primer positioning.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The primer insert is designed with specific geometric features including a precisely controlled primer recess and flash hole configuration that ensures uniform propellant ignition. This localized precision at the ignition source propagates uniform chamber pressure development throughout the cartridge, compensating for the inherent variability of polymer materials.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enhances the reliability and performance of polymer ammunition cartridges by providing consistent bullet pull and structural integrity, reducing the risk of jamming and damage, while being interchangeable with brass cartridges in existing weaponry.

Implementation Method 1

a molded primer insert for polymer ammunition comprising: an injection molded primer insert

Methodology Applied

Scientific EffectMetal injection molding:

Implementation Method 2

a substantially cylindrical coupling element extending away from the bottom surface forming an interior surface inside the substantially cylindrical coupling element and an exterior surface, a primer recess in the top surface that extends toward the bottom surface

Methodology Applied

Scientific EffectPolymer molding:

Data Source

PatentUS11300393B2Polymer ammunition having a MIM primer insert

Publication Date: 2022.04.12 TRUE VELOCITY IP HOLDINGS LLC

AI summary

One embodiment of the present invention provides a polymeric ammunition having a metal injection molded primer insert.