Method of Forming a Chamber for Polymer Ammunition

Abstract

The present invention provides a method of forming a chamber in a firearm wherein the chamber is adapted to fit a polymer ammunition cartridge comprising the steps of: providing a barrel blank; providing a reamer having the dimensions of the desired polymer ammunition cartridge, wherein the reamer comprising a reamer profile corresponding to an ammunition cartridge having a reduced neck height comprising: a shortened neck having a projectile aperture, wherein the shortened neck is reduced by 25-100% of the neck height of a standard cartridge neck; a shoulder extending from the shortened neck to a cartridge side wall; and wherein the cartridge side wall extends from the shoulder to the base to form an interior propellant chamber; wherein the base comprises an extraction ring, a primer recess positioned in the base in communication with the propellant chamber through a flash hole that extends from the primer recess into the propellant chamber; contacting the reamer with the barrel blank to form a reamed barrel having a chamber having the corresponding profile that mates to the reamer profile; removing the reamer from the reamed barrel.

What is claimed is: 
     
         1 . A method of forming a chamber in a firearm wherein the chamber is adapted to fit a polymer ammunition cartridge comprising the steps of:
 providing a barrel blank;   providing a reamer having the dimensions of the desired polymer ammunition cartridge, wherein the reamer comprising a reamer profile corresponding to an ammunition cartridge having a reduced neck height comprising: a shortened neck having a projectile aperture, wherein the shortened neck is reduced by 25-100% of the neck height of a standard cartridge neck; a shoulder extending from the shortened neck to a cartridge side wall; and wherein the cartridge side wall extends from the shoulder to the base to form an interior propellant chamber; wherein the base comprises an extraction ring, a primer recess positioned in the base in communication with the propellant chamber through a flash hole that extends from the primer recess into the propellant chamber;   contacting the reamer with the barrel blank to form a reamed barrel having a chamber having the corresponding profile that mates to the reamer profile;   removing the reamer from the reamed barrel.   
     
     
         2 . The method of  claim 1 , wherein the chamber is adapted accept a 5.56 mm, 7.62 mm, 12.7 mm, 14.5 mm, .223, .243, .277, .300, .308, .338, or a .50 caliber ammunition cartridge. 
     
     
         3 . The method of  claim 1 , wherein the polymer ammunition cartridge is a 5.56 mm, 7.62 mm, 12.7 mm, 14.5 mm, .223, .243, .277, .300, .308, .338, or a .50 caliber ammunition cartridge. 
     
     
         4 . The method of  claim 1 , wherein the shortened neck is reduced by 5 to 100% compared to the neck of a conventional ammunition cartridge. 
     
     
         5 . The method of  claim 1 , further comprising the step of treating the reamed barrel with a friction reducing substance. 
     
     
         6 . The method of  claim 1 , further comprising the step of heat treating the reamed barrel.