Confused

[90north]

I have a Thompson-Center conterder action. It has never had a pistol grip nor stock on it. I know that if I put a rifle stock on it, I need to have at least a 16" rifle barrel on it. If I want to use a shorter barrel on it I would have a SBR and have to comply with the NFA. My question, after registering it as a SBR can I use any under 16" rifle barrel on it, or only the one that was on it when I did the paper work?

[boofus]

You can put any length barrel on it after you get the paperwork back approved.