In weapon shot is fired during counterrecoil. The counterrecoil energy damps the recoil energy. During recoil, the breech block is unlocked, the spent cartridge case is ejected from the barrel by the residual pressure of the powder gases and is directed by a deflector into a hole in the gun carriage. When recoiling into the aftmost position, the barrel approaches the projectile and locks it by means of the breech block. Meanwhile, the next cartridge is taken from a magazine. In the event of misfire, the barrel, continuing to counterrecoil, actuates an extractor for removing the defective projectile. A recoil imitator returns the barrel to the aftmost position, where it is loaded with a projectile in a manner similar to the post-firing recoil. The technical result is ability to load the weapon automatically before firing or to reload the weapon automatically in the event of misfire.