Thanks for the posts!
My plan was to use the pistol adaptor for the purpose of traveling out of state after SBR approval. If I read the NFA Form correctly, I would need to put only the state I'm traveling to on my Form (and not all the states in between)...if the SBR was in pistol or rifle form while passing through those states (if legal within those states). I'd be sure to NOT also have the folding stock if in pistol form OR the short barreled upper if in rifle form, in my vehicle.
I may need to keep a full length rifle upper for my travel purposes instead, which is obviously a much more costly plan, vs just a pistol/stock adaptor, which I already have...the pistol adaptor, the folding stock, and the M4 tube adaptor too.
My Form1s are still newly submitted, so I have time to make plans for future ownership/travel, etc. I hate to think about it, but I may be better off to cancel my Form1, sell the CRB, and just go for another Form4 factory SBR (I have a Form1 and Form4 submitted, different calibers).
There's a machine shop in TX that has been cutting/threading Kriss barrels in their jig, without removing the barrel (I've seen the work and its 100%). There's also an experienced local gunsmith with the press that may be able to remove and cut/thread the barrel, then repress the barrel into the upper.