PURPOSE: To enable a cartridge bushing having propellent composing elements and liquids launched to be separately fed or charged by a method wherein a separating arrangement is formed as a cartridge base comprised of a propellent member and a closure member to be detachably connected to the end surface of the propellent member.

CONSTITUTION: A cartridge base 4 acting as a separating device between a powder charging chamber 2 and a liquid chamber 3 is fitted to an ammunition cylinder 1. A propellent composing element is fed from a feeding device to a ammunition cylinder supporting member 29 of a cannon tube 24. An amount of liquid to be launched is forcedly fed into an annular chamber between a closure element 21 and a propellent 5 of a cartridge base 4 under an operation of a pump 32 through an inlet opening 26 of the cannon tube 24 and then an axial separation of the closure member 21 from the propellent member 5 with liquid pressure. With such an arrangement as above, both seals for liquid at the cannon tube 24 is formed. The propellent 5 is held at that location when liquid is fed through a cartridge bushing 13 so as to form a rear seal against liquid. When the ammunition cylinder 1 is ignited, the propellent 5 in a cartridge base 4, liquid column in front of the cartridge base 4 and the closure member 21 for both of them are launched from the cannon tube 24.