Polymer cartridge with snapfit metal insert

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 at a second end opposite the first end, 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 is at least 0.010 inches in thickness;
• 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.