MAS-Mod-HK4_for Berliner Police:

The gauge is not indicated, the German HK-4 being a gun multi-gauges with conversions Barrel-chargers into 22Lr, 6,35mm Browning, 7,65mm Browning and 9mm Court Browning (ACP 380).

The head of cylinder head (single cylinder head for the 4 gauges) is equipped with a small rotary flask which, while turning of 180, off-sets the striker upwards, which makes it possible to pass instantaneously from the position central percussion to the annular position percussion.