Composite polymer based cartridge case having an overmolded metal cup, polymer plug base assembly

A cup and plug base assembly of a lead-free cartridge case configured to hold a projectile that has a cannelure formed along an outer circumferential surface thereof, the cartridge case including a cylindrical sleeve joined to the base, the sleeve being manufactured from a composite polymer and has a front end and a rear end opposite the front end, a mouth is defined by the front end of the sleeve and the rear end of the sleeve has an outer diameter that is less than an outer diameter of a main cartridge case holding chamber located intermediate the front and rear ends of the sleeve, the base assembly comprising:

• a cup having a web with a flash hole defined therein, a first annular cup portion extending in a first direction away from the web toward the sleeve and a second annular cup portion extending in a second direction away from the web and away from the sleeve in a direction opposite to the first direction in which the first annular cup portion extends;
• and
• a plug molded over the cup, the plug comprising a first annular portion extending from a first end of the base to a second end of the base and a second annular portion extending from the first annular portion and covers at least an entire inner surface of the first annular cup portion.