Engineered neck angle ammunition casing

Abstract

Polymeric ammunition casings having engineered neck geometries, and methods of forming such ammunition are provided. In particular embodiments, both the internal and external neck geometries are engineered to provide even greater improvement of the accuracy and consistency of the ammunition.

What is claimed is: 
     
         1 . An ammunition article comprising;
 a casing defining a generally cylindrical hollow body having internal and external walls, the casing having a cap at a first end thereof and a pressure vessel at a second end thereof, the pressure vessel having a proximal end defining a body region and a distal end defining a neck region, wherein the cap is interconnected with the proximal end of said pressure vessel such that the casing at least partially encloses an internal volume, and wherein the diameter of the pressure vessel narrows from a first diameter at the body region to a second diameter at the neck region;   wherein at least the neck region of the pressure vessel at least partially comprises a substantially polymeric material; and   wherein the geometry of the internal and external walls of the casing in the neck region of the casing are independent of each other.   
     
     
         2 . The ammunition article according to  claim 1 , wherein the casing in the neck region defines an internal wall that is linear and non-parallel with the external wall of the casing in the neck region. 
     
     
         3 . The ammunition article according to  claim 2 , wherein the external and internal walls in the neck region have define an external and internal angle relative to a longitudinal axis of the casing, wherein the angular ratio of the external angle to the internal angle is a non-unity value. 
     
     
         4 . The ammunition article according to  claim 3 , wherein the angular ratio is less than about 0.95. 
     
     
         5 . The ammunition article according to  claim 3 , wherein the angular ratio is greater than about 1.10. 
     
     
         6 . The ammunition article according to  claim 1 , wherein the casing in the neck region defines an internal wall that forms a generally circular arc relative to a linear external wall. 
     
     
         7 . The ammunition article according to  claim 6 , wherein the arc of the internal wall of the neck region defines a ratio of the radius of the arc to the length of the neck region of the casing of between about 0.1 and 50. 
     
     
         8 . The ammunition article according to  claim 1 , wherein the casing in the neck region defines an internal wall that forms a generally elliptical arc relative to a linear external wall. 
     
     
         9 . The ammunition article according to  claim 8 , wherein the elliptical arc of the internal wall of the neck region is defined by an ellipse value determined by the sum of the distances from any two points within a plane of the ellipse to any single point on the circumference of the ellipse, and wherein the ellipse value ranges from about 0 to 10 inches. 
     
     
         10 . The ammunition article according to  claim 1 , wherein the internal wall of the neck region is defined by a plurality of regions selected from the group of non-colinear consecutive lines, more than one arc in a spline curve, a combination of non-parallel lines, and a combination thereof. 
     
     
         11 . The ammunition article according to  claim 10 , wherein the plurality of regions are blended together using chamfers or fillets. 
     
     
         12 . The ammunition article according to  claim 1 , wherein the interior wall of the neck region of the casing has at least one point that is narrower than the inner diameter of the distal end of the pressure vessel in which a projectile would be inserted. 
     
     
         13 . The ammunition article according to  claim 12 , wherein the at least one point in the neck region is disposed such that a projectile inserted into the casing would impinge thereon. 
     
     
         14 . The ammunition article according to  claim 1 , wherein the casing is one-piece. 
     
     
         15 . The ammunition article according to  claim 1 , wherein the polymeric material comprises at least 10% of the casing by weight. 
     
     
         16 . The ammunition article according to  claim 1 , wherein the cap comprises a metal. 
     
     
         17 . The ammunition article according to  claim 1 , wherein the cap and the caselet are joined using an interconnection selected from the group consisting of a snap fit, threads, snap fit in conjunction with an adhesive, and threads in conjunction with an adhesive. 
     
     
         18 . The ammunition article according to  claim 1 , wherein the casing is closed at its distal end and contains no projectile. 
     
     
         19 . The ammunition article according to  claim 1  additionally comprising a projectile fitted into the distal end of the casing. 
     
     
         20 . The ammunition article according to  claim 11  wherein the projectile is secured to the casing by an interconnection selected from the group consisting of molding the polymeric material around the projectile, mechanical interference, an adhesive, ultrasonic welding, the combination of molding in place and adhesive, and hot crimping after molding. 
     
     
         21 . The ammunition article according to  claim 1 , wherein the pressure vessel comprises at least two pieces.