Polymeric Subsonic Cartridge with Nested Propellant Insert
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Solution Overview
Problem
Traditional methods for producing subsonic ammunition result in issues such as inconsistent propellant burn, reduced accuracy, and failure to efficiently cycle semi-automatic or fully automatic weapons due to the empty volume in the propellant chamber, leading to variations in velocity and potential weapon jamming.
Innovation Solution
A method involving a polymeric subsonic ammunition casing with a reduced propellant chamber volume, achieved by incorporating a propellant insert that reduces the internal volume of the propellant chamber by 25-80% compared to standard casings, utilizing a polymeric middle body and bullet-end component with a primer insert and propellant chamber design that includes ribs and a diffuser to manage pressure and ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the propellant chamber volume is reduced to achieve subsonic velocities, then the projectile velocity is reduced to subsonic range, but the empty volume causes inconsistent propellant burn and reduced accuracy
Solution Approach 1:
A propellant insert is nested within the propellant chamber, occupying the empty space between the propellant charge and the chamber walls. This nested structure eliminates the harmful empty volume while maintaining the reduced propellant quantity needed for subsonic velocities, ensuring consistent propellant burn and improved accuracy.
Solution Approach 2:
The propellant insert acts as an intermediary element that mediates between the reduced propellant charge and the propellant chamber walls. It provides a physical barrier that prevents propellant migration and ensures uniform burning, resolving the inconsistency caused by the empty volume.
2Speed
If the propellant charge is reduced to achieve subsonic velocities, then the projectile velocity is reduced, but the empty volume causes propellant detonation due to high burn rates
Solution Approach 1:
The propellant insert is nested within the propellant chamber to eliminate empty space, preventing propellant migration and ensuring uniform burn rates. This prevents the high burn rates that lead to detonation while maintaining subsonic velocities.
Solution Approach 2:
The propellant insert is positioned beforehand to cushion and contain the propellant charge, preventing it from migrating or burning too rapidly. This pre-positioned structure prevents detonation by ensuring controlled, uniform burn rates.
3Speed
If the propellant charge is reduced to achieve subsonic velocities, then the projectile velocity is reduced, but the chamber pressure is insufficient to cycle semi-automatic or fully automatic weapons
Solution Approach 1:
The propellant insert changes the physical parameters of the propellant chamber by reducing the effective volume and altering the burn surface area. This increases the chamber pressure and gas volume generated during combustion, enabling reliable cycling of semi-automatic and fully automatic weapons while maintaining subsonic projectile velocities.
Solution Approach 2:
The nested propellant insert structure optimizes the combustion chamber geometry, increasing pressure efficiency. This allows the reduced propellant charge to generate sufficient chamber pressure for weapon cycling despite the lower velocity requirement.
4Speed
If traditional methods are used to reduce propellant charge for subsonic ammunition, then the velocity is reduced, but the empty volume requires complex solutions such as inert fillers, expandable inner sleeves, or foamed inserts
Solution Approach 1:
The propellant insert is a simple nested structure that occupies the empty space in the propellant chamber. This straightforward nested design eliminates the need for complex inert fillers, expandable sleeves, or foamed inserts, reducing cartridge structure complexity while effectively eliminating empty volume.
Solution Approach 2:
The invention extracts the problematic empty volume from the propellant chamber by introducing a simple propellant insert. This extracted approach eliminates the need for complex multi-component solutions, simplifying the overall cartridge structure.
Data Source
AI summary
The present invention provides a method of making a subsonic ammunition cartridge having a polymeric casing body having a generally cylindrical hollow polymer body having a body base at a first end thereof and a mouth at a second end to define a propellant chamber; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber, wherein the propellant chamber has an internal volume that is between 25 and 80% less than the open internal volume of a standard casing of equivalent caliber; and a primer insert positioned in the body base and in communication with the propellant chamber.