Yes, it's a confusing thread title. That's because I have a convoluted question. I have a legally owned (Form 1) AR 15 lower that is currently mated to a 10" upper with a silencer in 300 Blackout. I live in northern KY not too far from both the Ohio and Indiana borders and my travels sometimes take me into both states. I'm usually driving the same car that I take to the range, so there's always the possibility that absent minded me might just leave my SBR in the trunk. As I'm sure many people know, the NFA requires asking permission in advance to take an SBR out of state, but does not require this of silencers. Both IN and OH allow silencer ownership and neither have magazine capacity restrictions. Last weekend I happened to see a 'pistol brace' that I really liked. It's the Tailhook Mod 2 from Gearhead Works, and IMO it's the best of the braces. They have an ATF letter approving it as a pistol brace. So, here's what I'm wondering: what if I install a Tailhook brace on my SBR lower? When combined with the 10" upper does it legally become a pistol in spite of the fact that it has a stamp as an SBR? I ask because I know that if I add a 20" upper it no longer is an SBR. It's well established that it's only an SBR when in SBR configuration. Is it only a rifle when in rifle configuration? It would be nice to be able to leave my 'pistol' in the car and not have to worry about becoming a felon when crossing the river. It would just be traveling with an AR pistol, but I could throw it up to my shoulder earn back in Kentucky and not have to worry about the whole "redesign" thing. Or does "once a rifle, always a rifle" always apply? FWIW, the lower in question was bought new as an assembled lower and was not mated to a rifle upper when I purchased it. Thoughts?