One of the things I see in this thread is a bunch of misinformation. About half of you don't know what the rules are for your state and the other half doesn’t know what is legal and what is not. Do your research and then make an informed decision. NFA laws are Federal make sure that ha rifle has a minimum of a 16” barrel and a shotgun has at least an 18” barrel, If you want a barrel length shorter than 18” you have to pay the $5 tax stamp and classify it as an AOW (any other weapon). Short barreled rifles are a $200 tax stamp and a same with suppressors (if you can own them in your state). Paperwork on these things take a minimum of 3-4 months so it’s better to go with an 18” barrel shotty. Rifles are too powerful background becomes a problem.
Jeff
This is what you need:
http://autoweapons.com/photosv/supershorty.html