SKM was a small industrial manufacturing company in Croatia that began making submachine guns in 1991 to equip Croatian fighters in the Homeland War. Their product was the M91 Crogar, which is a selective-fire, open bolt SMG chambered for 7.62mm Tokarev. It uses the magazine from the Yugoslav M56 SMG, along with its rotating bolt handle feature as a safety mechanism. The bolt and recoil spring are based on the MP40, and a folding stock inspired by the side-folding AKs made in Poland, Romania, and Hungary. Total production quantity is not known, but was not more than a few hundred at most. The build quality on these guns was quite good, and they were reportedly well liked by those who got them.
A big thanks to the Croatian Police Museum (Muzej Policije) in Zagreb for giving me access to film this rare piece for you! Check them out at: https://muzej-policije.gov.hr