Abstract: An important factor in firearms suitable for combat is the capability to permit replacing the magazine with one hand, that is, to permit the user to eject an emptied magazine by releasing it with the shooting hand and permitting it to drop out automatically, so that a full magazine can be inserted with the free hand. To accomplish this, a latch mechanism is arranged in a through hole formed transversely to the magazine opening and to the longitudinal axis of the barrel of the gun and includes two positive detent latches in a concave or arched portion, the detents being separated by a central groove. The detents have an outer arched or curved surface and on the inside provide straight walls for the groove, in this way a straight magazine can displace the latch axially. The magazine has two pairs of recesses in a rounded leading surface that are arranged so that the two detents seat in the recesses, thereby to accurately support the magazine in two dimensions.