Polymer cartridge with snapfit metal insert
A high strength polymer-based cartridge has a polymer case with a mouth, a neck, a shoulder below the neck, and a body below the shoulder and having a case thickness (Tc). The body has a flat portion comprising a pull thickness (Tp), and a dip, closer to the shoulder than the flat portion and comprising a dip thickness (Tb). The cartridge can also include an insert attached to the polymer case opposite the shoulder. The insert can have a flat section contacting the flat portion and comprising an insert wall thickness (Ti), and a bulge engaging the dip to maintain the insert on the polymer case. Tc, Tp, Tb, and Ti are related by Tp+Tb+Ti=Tc. These variables also have ranges where Tp equals approximately 15-33% of Tc, Tb is greater than or equal to Tp, and Tc is a function of a loaded projectile.
1. A high strength polymer-based cartridge, comprising:
a polymer case, comprising:
a first end having a mouth;
a neck extending away from the mouth;
a shoulder extending below the neck and away from the first end;
a body formed below the shoulder and having a case thickness (Tc), comprising:
a flat portion comprising a pull thickness (Tp); and
a dip, closer to the shoulder than the flat portion and comprising a dip thickness (Tb);
an insert directly attached to the polymer case opposite the shoulder, comprising:
a flat section contacting the flat portion and comprising an insert wall thickness (Ti); and
a bulge engaging the dip to maintain the insert on the polymer case; and
a projectile disposed in the mouth having a particular caliber;
wherein the case thickness, the pull thickness, the dip thickness, and the insert wall thickness are related as follows:
Tp+Tb+Ti=Tc;
wherein Tp equals approximately 15-33% of Tc;
wherein Tb is greater than or equal to Tp; and
wherein Tc is a function of the projectile and a ballistic performance for the projectile.