Looks like a variant of a Polish machine pistol PM63:
PM 63
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Pm-63 is blowback operated. It fires from open bolt and the slide must be racked back to cock it. It is equipped with a retractable sheet metal stock and a folding plastic forward pistol grip. Pm-63 is capable of both semi- and automatic fire but is not equipped with a selector. Semi-automatic fire is achieved by a short pull on the trigger and full-automatic fire requires the trigger to be pulled all the way back. Manual safety is located on the left side in the upper rear part of the pistol grip. The 15 or 25 shot double-column magazines are inserted in the pistol grip and the magazine release is located, as in others Eastern block weapons of that era, at the bottom of the grip. The elongated, forward part of the slide works as a muzzle-flip reducer and can also be used to cock the slide one-handed (by pressing it against a solid object). Rear part of the frame houses a cyclic rate reducer which reduces the rate of fire to 650 rpm making the Pm-63 very controllable despite it's small size and light weight. Sights can be set on 75 or 150 meters. Since their are mounted directly on the slide which is in constant motion during firing only the first shot can be well directed. But when fired in short bursts this gun can be quite accurate, especially at short ranges. Pm-63 is made entirely from steel to a suprisingly high standard making it quite expensive to manufacture. Standard equipment consist of a carrying belt, a canvas holster, magazine pouch, cleaning gear and four magazines (one 15 rounds and three 25 rounds). The smaller magazine is usually carried on the weapon, with three spares in the magazine pouch. A shoulder holster for undercover work is also available.
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