Myself I have a feeling this barrel has been cut after leaving the factory at some point in time. Just something about how it looks as the crown is too big for the normal size I think. I don't recall ever seeing the Muzzle brake going in so far on any M41 that I have ever seen. I have the 73/8th barrel on mine with the brake and the end of the barrel is flush with the brake and not indented inward. I wonder what the serial no. range is? It almost looks like heat marks near the end of the barrel left by cutting marks as well. Of course it could be my eyes playing tricks as well.