Cute little gun - Sa 81 KRÁSA. It's a PDW chambered in 7,62x39mm, from Czech VVU ZVS in Brno, developed in late 70-s. As you can see - it is gas-operated, utilized some sort of sliding-block locking mechanism and has pretty interesting feeding mechanism, which pulled cartridges from the magazine backwards before chambering them. Such complication was implemented to increase the barrel length while keeping overall size as short as possible. This gun have a ~190mm(just 20mm shorter than AKS-74U which is 490mm in folded config) barrel and 315mm length while stock folded, pretty cool! Also it's light - 2.1 kg empty.