Ammunition cartridge with a base plug vent

Abstract

An ammunition cartridge comprised of a projectile inserted in, and mechanically connected to, a metal cartridge case assembly having a propulsion chamber and a base, and an energetic propellant disposed in the propulsion chamber, includes a base plug in which is mounted an igniter with an energetic primer. During manufacture of the cartridge, a fusible support ring is incorporated into a metal cavity. The cartridge base includes a cavity allowing the fusible material to solidify at ambient temperatures. When exposed to heat from an external fire, the fusible support plug liquefies losing its strength and subsequently, when a propellant or primer off-gasses or auto-ignites the pressure from the reaction ejects a metal plug or lid from the cartridge case base, creating a void that allows the propellant and primer to combust in an unconfined space.

1 . A ammunition cartridge incorporating a projectile inserted in, and mechanically connected to a metal cartridge case assembly having an energetic propellant disposed in a combustion chamber;
 wherein a base of the cartridge case assembly incorporates a base plug configured to incorporate a support plug fabricated from a fusile material that, when completely assembled, the ammunition cartridge's sub-assembly is filled with a propellant and fit with an energetic igniter or primer that seals a combustion chamber;   wherein the cartridge case assembly incorporates a cavity and mold allowing for injection of the fusible material forming the fusible support plug into the base of the cartridge, during the manufacturing process to fabricate the cartridge; and   wherein said fusible material loses its strength and structural integrity at elevated temperatures such that, when the propellant or primer off-gasses or auto-ignites, the base plug is ejected from the base of the cartridge, revealing a channel that allows igniting energetic materials to burn in an unpressurized state and vent gases to escape into an unconfined space.   
     
     
         2 . The ammunition cartridge of  claim 1 , wherein the fusible material is a polymer. 
     
     
         3 . The ammunition cartridge of  claim 1 , wherein the fusible material is a fusible metal. 
     
     
         4 . The ammunition cartridge of  claim 1 , wherein the base plug is formed of a solid material having a strength at normal munition operating temperatures that is sufficient to maintain structural integrity through normal cartridge operating pressures of a feeding, firing, extraction and ejection cycle of the munition. 
     
     
         5 . The ammunition cartridge of  claim 1 , wherein the auto-ignition of the propellant vents gases from the void created by ejection of the base plug. 
     
     
         6 . The ammunition cartridge of  claim 5 , wherein the void is of such size as to preclude pressurization of the propulsion chamber, minimizing the imparted energy acting on the projectile affixed to the cartridge case. 
     
     
         7 . The ammunition cartridge of  claim 6 , wherein the size of the void, created by ejection of the base plug, is selected to be in proportion to the type and amount of propellant. 
     
     
         8 . The ammunition cartridge of  claim 1 , wherein the fusible material forms an O-ring shape surrounding the base plug. 
     
     
         9 . The ammunition cartridge of  claim 8 , wherein the fusible material surrounding the base plug further includes projection from the O-ring shape that extends rapidly outward into at least one passage in the base of the cartridge case, thereby retaining the physical connection of the base plug to the cartridge case during ejection after firing and reducing the energy imparted on the ejection base plug. 
     
     
         10 . The ammunition cartridge of  claim 1 , wherein the internal cavity is circular in shape; the base includes a plurality of passages extending radially outward from the internal cavity to the exterior; and wherein the fusible material includes a plurality of projections extending radially outward through said passages. 
     
     
         11 . An ammunition package for multiple cartridge munitions having a base plug affixed with fusible material in accordance with  claim 1 , wherein said package incorporates packaging material that retains its form and strength at elevated temperatures and provides an undeterred vent path for release of pressure in the event the base plug is ejected. 
     
     
         12 . An ammunition package containing multiple cartridges that incorporate a base vent retained by fusible material in accordance with  claim 1 , said package including a dunnage with a configuration allowing for unobstructed venting of the base of said multiple cartridges therein and incorporating a blow-out panel in a wall of the package that relieves any momentary pressurization within the package by breaking away and allowing gases to vent from a punctured panel into the atmosphere. 
     
     
         13 . The ammunition package of  claim 12 , wherein the dunnage is selected so as not to melt and re-congeal or clog vented cartridges. 
     
     
         14 . A method of manufacturing an ammunition cartridge comprised of a projectile inserted in, and mechanically connected to, a metal cartridge case having a propulsion chamber and a base, and an energetic propellant disposed in the propulsion chamber;
 wherein the base has a central internal cavity that is provided with an ejectable, solid base plug in which is mounted an igniter with an energetic primer; and   wherein the base includes at least one passage from the internal cavity to the exterior;   said method comprising the steps of:   (a) inserting a solid base plug into said internal cavity of the base forming an interface between the base plug and the base that surrounds it;   (b) injecting a fusible material at an elevated temperature through said at least one passage into said interface and allowing said fusible material to solidify at an ambient temperature; and   (c) mounting an igniter with an energetic primer in said base plug.   
     
     
         15 . The method of  claim 14 , wherein the fusible material is a polymer. 
     
     
         16 . The method of  claim 14 , wherein the fusible material is a fusible metal.