It has been a long time dreaming, and now I have this little fella in my hands!
Correct, 20in barrel. The flash hider threads on, and is pinned in place.Looks great. I wish thee was a HK433 variant like this. So the barrel is 20" if I'm correct. Also, is the muzzle device pinned or is that a screw that can be loosened or tightened? I'm asking because most normal HK muzzle devices are held on with a retainer spring and a tapered section behind the threads. But since the bottom is blanked off (to function as a muzzle brake/comp), it does have to be timed more exactly than the normal HK flash hiders.