Neck polymeric ammunition casing geometry

A polymeric ammunition casing comprising:

• a cylindrical hollow body defining an internal cavity formed at least partially of a polymeric material, the cylindrical hollow body further defining a longitudinal axis and having a closed primer end and an open projectile end, wherein the body is formed of a body portion proximal to the primer end and a neck portion proximal to the projectile end, and wherein the diameter of the cylindrical hollow body tapers such that the diameter of the body portion is larger than the diameter of the neck portion;
• wherein the longitudinal length of the neck portion of the polymeric ammunition casing is greater than the longitudinal neck portion length of a conventional metal ammunition casing body of a comparable caliber;
• and
• further comprising a cylindrical strip of a polymeric material disposed within the internal cavity of the ammunition casing along at least the portion of the neck portion of said ammunition casing that engages the cannelure of a projectile.