The subject invention concerns a general method of producing countermass weaponry and is based on the use of a high-pressure system and a low-pressure system with a countermass (12, 26, 26, 38) acting against the low-pressure system. The high-pressure system (7, 23, 23, 36) shall, in practice, be formed by the combustion chamber for the weapon propellant charges (8, 22, 22, 35) while the main part of the low-pressure system (25, 25) shall, in initial stages, be formed by the storage and acceleration chamber for the countermass. The advantage of the subject invention is that said invention offers a possibility of achieving lower pressure levels around the grunner without, for such an end, diminishing the range of the weapon (1, 13).