Nice gun! They were known by various names in the US, depending on who imported them: K1/K2, MAX-1/MAX-2, AR-100/AR-100C. I still have my pre-ban AR-100C. It was interesting that the rifle version, as you have, and the short version with the collapsible wire stock used different gas system. The short version had a DI system like an AR, while the rifle version has a long stroke piston system like an AK. The rifle version also has a 4 position adjustable gas regulator.
For the flash hider, they may not have cut down the barrel. Bushmaster sold a XM177 looking flash hider that was threaded just behind the slots and most of the hider slipped over the barrel so you could have the shorty look without having to cut the barrel and worry about going SBR or pinning the hider.