The PAK-9 is a semi-automatic, blow-back operated pistol based on the AK platform.
The PAK-9 doesn’t have a traditional AK piston-driven gas system. Unlike the original WASR, It uses detachable pistol magazines that are inserted via an adapter that fits in the standard AK mag well.
From Atlantic Firearms, this adapter is configured to utilize Beretta 92 magazines. However, (and to me, this is perhaps the most appealing feature of the gun), the PAK-9 comes with the capability to use different magazine patterns with a simple swap of the mag well.