A system for fastening the barrel (1) of a rifle with a replaceable barrel, the system consisting of a lock frame (2), into which the barrel socket (5) can be inserted into position and locked by a bolting device. The bolting device consists of a barrel block stop (4) provided at the top of the lock frame (2), a groove (6) in the barrel socket being insertable into the block stop when the barrel is clamped into locked position.