The present invention discloses a lightweight hybrid cartridge case (100) for a cartridged ammunition and a method of manufacture (200). The lightweight hybrid cartridge case (100) includes a cap (110) with a cylindrical sidewall (112) connected a base (120); a polymer shell (150) is insert-molded onto the sidewall of the cap; and an overmolded sleeve (180) is formed to cover the metal-polymer joint between the cap (110) and the polymer sleeve (150). The cylindrical sidewall (112) covered by the overmolded sleeve (180) has a plurality of stepped ridges (132, 132a), preferably with one stepped ridge (133) having a C-stepped edge (134).

The present invention provides a method of making a metal injection molded ammunition cartridge comprising the steps of: providing an ammunition cartridge mold comprising a bottom portion having a primer recess extending into the bottom portion adapted to receive a primer, a flash hole positioned in the primer recess through the bottom surface; side walls extending from the bottom portion to a nose end aperture, wherein a propellant chamber is formed between the nose end aperture and the bottom surface; injecting a metal composition into the ammunition cartridge mold to form a metal injection molded ammunition cartridge; and removing the metal injection molded ammunition cartridge from the ammunition cartridge mold.

The present invention provides a method of making a metal injection molded ammunition cartridge comprising the steps of: providing an ammunition cartridge mold comprising a bottom portion having a primer recess extending into the bottom portion adapted to receive a primer, a flash hole positioned in the primer recess through the bottom surface; side walls extending from the bottom portion to a nose end aperture, wherein a propellant chamber is formed between the nose end aperture and the bottom surface; injecting a metal composition into the ammunition cartridge mold to form a metal injection molded ammunition cartridge; and removing the metal injection molded ammunition cartridge from the ammunition cartridge mold.

The present invention provides a subsonic ammunition including a polymeric casing body; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber; a propellant disposed and confined within the propellant chamber; a primer insert positioned at the body base and in communication with the propellant chamber; a primer and diffuser disposed in the primer insert in combustible communication with the propellant; and a projectile frictionally fitted in the mouth in combustible communication with the propellant.

The present invention provides a subsonic ammunition including a polymeric casing body; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber; a propellant disposed and confined within the propellant chamber; a primer insert positioned at the body base and in communication with the propellant chamber; a primer and diffuser disposed in the primer insert in combustible communication with the propellant; and a projectile frictionally fitted in the mouth in combustible communication with the propellant.

The present invention provides a method of making a metal injection molded ammunition cartridge comprising the steps of: providing an ammunition cartridge mold comprising a bottom portion having a primer recess extending into the bottom portion adapted to receive a primer, a flash hole positioned in the primer recess through the bottom surface; side walls extending from the bottom portion to a nose end aperture, wherein a propellant chamber is formed between the nose end aperture and the bottom surface; injecting a metal composition into the ammunition cartridge mold to form a metal injection molded ammunition cartridge; and removing the metal injection molded ammunition cartridge from the ammunition cartridge mold.

The present invention provides a method of making a metal injection molded ammunition cartridge comprising the steps of: providing an ammunition cartridge mold comprising a bottom portion having a primer recess extending into the bottom portion adapted to receive a primer, a flash hole positioned in the primer recess through the bottom surface; side walls extending from the bottom portion to a nose end aperture, wherein a propellant chamber is formed between the nose end aperture and the bottom surface; injecting a metal composition into the ammunition cartridge mold to form a metal injection molded ammunition cartridge; and removing the metal injection molded ammunition cartridge from the ammunition cartridge mold.

The present invention provides a subsonic ammunition including a polymeric casing body; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber; a propellant disposed and confined within the propellant chamber; a primer insert positioned at the body base and in communication with the propellant chamber; a primer and diffuser disposed in the primer insert in combustible communication with the propellant; and a projectile frictionally fitted in the mouth in combustible communication with the propellant.

The present invention provides a subsonic ammunition including a polymeric casing body; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber; a propellant disposed and confined within the propellant chamber; a primer insert positioned at the body base and in communication with the propellant chamber; a primer and diffuser disposed in the primer insert in combustible communication with the propellant; and a projectile frictionally fitted in the mouth in combustible communication with the propellant.

A firearm cartridge case includes a cartridge case having a base which defines a cartridge case diameter; and a rebated rim which defines a rim diameter less than the cartridge case diameter, a ratio of the cartridge case diameter to the rim diameter is between 1.03-1.10.