Originally Posted by smince
I've seen a letter from ATF saying that the gun had to be transported and stored in SBR configuration and could only be put back into pistol configuration for a short time at the range. Since the gun is now registered as an SBR (not a 'pistol' anymore) this makes sense.
If you have a link to this letter, I would like to see it.
I have a SBR 9mm AR style. I have discussed transporting this firearm into states that have outlawed SBR's. I have been informed by ATF and the State Police of that state that as long as the rifle is in "legal configuration" you can transport it into the state. They don't care if it's on the NFA registry or not, as long as you leave the short barrel at home, you're fine.
The thought process is that weather it's on the NFA registry, or NOT, you can change the configuration as you wish. When it's a PISTOL, it's a pistol. When you put the stock on it, it's an SBR, and the SBR rules would apply.
Since I am waiting on the Form 1 for my Glock, I will indeed write a letter to the ATF to ask them about this very topic, but I would expect this to take a year or so before I get an answer back. (I have written one letter in the past, and have yet to hear from the ATF.)