Patent ID: 11262171

Abstract:
A casing for use in a cartridge for a firearm comprises a sleeve portion and a base portion, where the base has cannelure comprised of curving surfaces. In a casing embodiment, a sleeve has cylindrical portion with a mouth for holding a bullet and an opposing end radially-running bulkhead. A nipple extends from the bulkhead and into a passageway of the base, thereby securing the sleeve to the base. The sleeve bulkhead preferably has at least one circumferential wave and contacts a distal end surface of the base, which may be planar or conical. The cannelure is characterized by a continuously curving groove bottom, a maximum groove depth diameter that is 60 to 80 percent of the base outside diameter, and a volume that is 20 to 43 percent of the volume of a like base which has no cannelure.