Is a rifled shotgun barrel a rifle or a shotgun?
Neither. It's a barrel. As nobbie333 pointed out, a shotgun sporting a rifled barrel is still a shotgun.
Than if you have a Thompson Center Arms Contender pistol can you put a rifled shotgun barrel without getting a aow tax stamp?
The TC shotgun barrels are 24" aren't they? I think that alone takes them outside the realm of AOW.
The barrel is longer than 18" and the overall length is over 26".
The 45 Colt/.410 barrel is still a rifled pistol barrel I believe. (like the 45/410 Judge "snubby")
ATF.Gov is only a search away.
Asking questions of gun legality on a forum is never a good idea. Any free advice is usually worth what you paid for it.
Would you put your butt on the line, and possibly in federal prison, because somebody on the internet said it was OK? Better you than me...
CHECK THE LAWS OF BATF AND IN
YOUR STATE!!
If nothing else, you can contact Thompson Center and ask. They don't want you to violate the laws any more than we do!