I hacksawed a mosin barrel and it shot as normal as it did before I cut it. Like 12" targets at 250 yards with a scope was very easy with very bad ammo.If this were a shotgun or a 22 rifle made with normal steel, I'd use a hacksaw.
BUT, considering how hard Norinco barrel steel is, I think I would use a metal cutting blade in my chop saw. ( After building a wooden support for the barreled action so that the gun's barrel would be completely perpendicular to the cut and held steady during the cut.)
Is it a pain to get to the gas port hole? I wouldn't be afraid to just drill it a little bit and reassemble and see what happens?