Abstract: A subsonic cartridge that enables a conventional automatic or semiautomatic weapon to fire a projectile at a subsonic velocity and cycle the weapon to eject the spent cartridge case, without the sonic report characteristic of supersonic projectile velocities. The cartridge includes a case having a tubular shape with an open end oppositely disposed head, and a bore therebetween. The head of the case includes a primer cavity, a web separating the primer cavity from the bore, and a flash hole through the web. A primer is stored within the primer cavity, and projectile is disposed within the bore so as to close the open end of the cartridge case. A charge cavity is delimited within the bore between the web and the projectile. The charge cavity is sized and shaped to contain a limited amount of propellant charge that propels the projectile from the cartridge case at a subsonic speed.