Yes. Two methods.
1. Remove the stock from the tube and you have a pistol (you dont need a "pistol" tube); or
2. Replace the upper with a 16" barrel and you have a long-gun
If you intend the change to be permanent, the NFA branch requests that you send a letter asking to remove the receiver from the NFA register.
If you do #1 you'll probably want to sell the stock
If you do #2 you'll probably want to sell the upper or buy a pistol receiver
Question to the guys that are a little more experienced with NFA stuff...
I picked up a 9" upper the other day to mate with a (new, never been a rifle) lower I've had laying around, and got to wondering...
Once you create an SBR on a Form 1, can you ever take it back down to a full length 'Title one' firearm? I ask because the options are either build this thing as a pistol or send in a Form 1.
My major concern is, I eventually plan to move to and retire in Washington state- where SBR's are a no-go. I'm wondering if upon a move I could just "un-sbr" the thing and take it out of the NFA category or once it's registered as SBR is it a done deal?