gyvel And the age old question rears its ugly head once again: If you put a 16" rifled barrel on your shotgun, is it illegal?
It's not an age old question.
It's also not illegal.
Putting a rifled barrel on a SHOTGUN does not change the fact it is a shotgun.
The NFA of 1934 says any SHOTGUN with a barrel length of less than 18" requires a tax stamp for a short barrelled shotgun.
Short barrelled shotguns are perfectly legal.........with a tax stamp.