Abstract: A semi-automatic pistol is created by the modification of a fully automatic sub-machine gun Sa vz. 61. The semi-automatic pistol is constructed partly from original parts of the Sa vz. 61 sub-machine gun, i.e. barrel, receiver, trigger, trigger lever and pistol grip, partly from modified parts of Sa vz. 61 sub-machine gun, i.e. hammer, interrupter and bolt, and partly from newly manufactured parts, i.e. semi-automatic frame without a groove in the bridge for the release lever and openings in rear stop for retarder assembly and without rails for folding stock on the outside of the rear wall, and a new safety lever with holes and grooves in such a positions that only semi-automatic fire is possible in its forward position. Some parts of the Sa vz. 61 sub-machine gun are removed completely, i.e. original frame, original safety lever, release lever, folding stock and retarder group (bolt hook, weight, counterweight, spring).