Medium caliber polymer ammunition cartridge

Abstract

A medium caliber polymer-based ammunition cartridge has an insert forming a base end and engaged to a polymer body forming an internal propellant chamber. The polymer body is engaged at its forward end to a polymer nose which has a shoulder that transitions directly into a projectile opening. The shoulder is inwardly radially thickened to increase lateral support about a medium caliber projectile loaded into the cartridge. The thickness of the shoulder may vary along its longitudinal length. One or more crush seals may be integrally formed about an outer surface of the cartridge nose. The crush seals include an annular tip seal and one or more annular shoulder seals. Each of the crush seals deform into an obturating ring to form a seal between the outer surface of the medium caliber polymer cartridge and the inner walls of the firing chamber.

1 - 20 . (canceled) 
     
     
         21 . A medium caliber polymer-based ammunition cartridge, comprising:
 an insert having a top surface and a bottom surface, a coupling element extending from the top surface, a primer pocket formed through the bottom surface, and a flash hole in fluid communication with the primer pocket and extending through the top surface;   a polymer body engaged to the insert forming an internal propellant chamber, wherein a first end of the polymer body is molded about the coupling element and into the flash hole and wherein a second end, opposite the first end, forms a nose joint;   a polymer nose engaged to the nose joint of the polymer body, the polymer nose having a shoulder transitioning into a projectile opening, and an internal annular ridge having a proximal side and a distal side connected by a flat surface, wherein the annular ridge is configured to engage a cannelure defined in an outer surface of a projectile configured to be loaded into the projectile opening.   
     
     
         22 . The cartridge of  claim 21 , wherein the proximal side of the annular ridge is slanted defining a first angle. 
     
     
         23 . The cartridge of  claim 22 , wherein the first angle is less than 90-degrees. 
     
     
         24 . The cartridge of  claim 22 , wherein the distal side of the annular ridge is slanted defining a second angle. 
     
     
         25 . The cartridge of  claim 24 , wherein the second angle is less than 90-degrees. 
     
     
         26 . The cartridge of  claim 24 , wherein the first angle and the second angle are configured to generate a bullet pull force of at least 100 pounds of force when the cartridge is not supported in a firing chamber. 
     
     
         27 . The cartridge of  claim 24 , wherein the first angle and the second angle are the same. 
     
     
         28 . The cartridge of  claim 21 , wherein the polymer nose further comprises an internal annular seat formed proximate the projectile opening, the annular seat configured to seat a driving band engaged around an outer surface of a projectile loaded into the projectile opening. 
     
     
         29 . The cartridge of  claim 28 , wherein the polymer nose is configured to fully enclose the driving band of the projectile loaded into the projectile opening. 
     
     
         30 . The cartridge of  claim 28 , wherein an internal distal end of the polymer nose comprises a beveled tip. 
     
     
         31 . The cartridge of  claim 30 , wherein the internal annular seat defines an internal diameter greater than an outer diameter defined by the driving band to form a gap between an inner wall of the projectile opening and the driving band. 
     
     
         32 . The cartridge of  claim 31 , wherein the gap is configured to receive a sealant. 
     
     
         33 . The cartridge of  claim 28 , wherein the polymer nose is configured to partially enclose the driving band of the projectile loaded into the projectile opening. 
     
     
         34 . The cartridge of  claim 28 , wherein the internal annular seat defines an internal diameter substantially equal to an outer diameter defined by the driving band. 
     
     
         35 . The cartridge of  claim 21 , wherein the polymer nose has a thickness that varies from the nose joint to the projectile opening. 
     
     
         36 . The cartridge of  claim 21 , wherein the polymer nose further comprises one or more crush seals formed on an outer surface. 
     
     
         37 . The cartridge of  claim 36 , wherein each of the one or more crush seals are configured to deform into an obturating ring when crushed under the forward axial movement of the cartridge in a firing chamber. 
     
     
         38 . The cartridge of  claim 37 , wherein the one or more crush seals comprise an annular tip seal formed at a distal end of the polymer nose. 
     
     
         39 . The cartridge of  claim 37 , wherein the one or more crush seals comprise a plurality of annular shoulder seals formed around an outer surface of the shoulder. 
     
     
         40 . The cartridge of  37 , wherein the one or more crush seals comprise at least one annular tip seal formed at a distal end of the polymer nose and at least one annular shoulder seal formed around an outer surface of the shoulder.