This is lot #545 in the upcoming RIA Premier Auction. It was scheduled for April, but has been postponed – check their web site for upcoming Online Only auctions every month, though!
The K-50M was a North Vietnamese modification of the PPSh-41 submachine gun to mimic the handling of a French MAT-49. Made from Chinese Type 50 guns (which were direct copies of the original PPSh-41) in small shops, the K-50M used a wholly new lower receiver assembly. This new lower fitted an AK pistol grip and a collapsing wire stock patterned after the MAT-49. The barrel was kept intact, but the barrel shroud was shortened, the muzzle brake/compensator removed, and a new AK (or SKS) style of front sight block added. Mechanically, the guns remained unchanged, firing from an open bolt in 7.62x25mm Tokarev caliber, with the semiauto selector switch of the original Shpagin. The K-50M is compatible with PPSh-41 drums (allowing for fitting issues), but was issued with 35-round box magazines.