Rem 1000 Chop Job
I had the same question about shortening a barrel as a do-it-yourself project, so I called CFC. They told me that as long as you respect the 26" overall and 18.5" barrel length rules, it will not change the status of a non-restricted firearm. I talked to a technical advisor and he even told me the lengths that the CFC recognizes as factory sizes. That was really helpful for deciding what length to use for my project.
Best of all, the call dispelled the BS I was told by a guy who said that you have to have a certified gunsmith shorten your barrel to stay legal. He's a certified gunsmith. Hmmmm... I figured I'd call the CFC to see if there was anything to it. I may be relatively new to the hobby/sport/addiction of building, shooting and collecting firearms, but I wasn't born yesterday.
That said, I shortened my Rem 1100 barrel just today at work during lunch. I used a hacksaw and a lathe then filed the vent rib. It went quickly and turned out nice and square. Now if only the last parts I ordered for my project would arrive....