Contoured Thickness Blank for Ammunition Cartridges

Abstract

An austenitic stainless steel ammunition cartridge includes an outer region and a base, wherein the outer region is about 50%-80% of the thickness of the base, which serves to minimize the sidewall ironing required to form the cartridge. The cartridge blank can be formed by spin forming, compression forming, grinding, or a combination thereof. Tooling to form the insert can include at least a pair of blocks and inserts, at least one insert defining a centrally positioned aperture.

1 . A method of forming an ammunition cartridge, comprising the steps of:
 (a) forming a blank having a button and an outer region and a central axis, the outer region peripherally surrounding the button, the outer region and the button of the blank each having a substantially linear underside that is substantially perpendicular to the central axis;   (b) forming the underside of the outer region downwards in a direction toward the central axis until the outer region is substantially parallel to the central axis.   
     
     
         2 . The method of  claim 1 , wherein the forming process for the blank comprises at least one of spin forming or compression forming. 
     
     
         3 . The method of  claim 1 , wherein the forming process for the blank comprises grinding. 
     
     
         4 . The method of  claim 1 , wherein the blank is pre-annealed. 
     
     
         5 . The method of  claim 1 , wherein the forming process for the blank comprises compression forming with tooling comprising a pair of blocks and a pair of inserts, each block configured to receive a respective insert. 
     
     
         6 . The method of  claim 5 , wherein at least one insert includes a central aperture therein.