Actually the barrel could be less then 18", remember it's measured from the muzzle to the bolt breech face.
As far as cutting it off a hacksaw works fine then chuck it up in a lathe and clean it up
I've had good luck cutting them down with a hacksaw. Only problem you might encounter is if it's a vent rib since it's hollow. Same goes for a double barrel and the channel between the 2.
Really!?
Well that's easy enough. Thanks!
BTW (to all), I was asking about the 'mechanics'.... not the legality, of cutting her down.
you can cut it with a pipe cutter but I guess you can crack the barrel if you try to go to fast. A buddy cut his down with a pipe cutter and the ran a chamfer tool in a hand drill to clean it up.
I think you'll probably bust your cutter before the barrel. The tool is harder and more brittle than the (comparatively ductile) barrel.