Ok Slick, its apparent you are one of those “Sovereign citizen” types so here are my answers to your questions above.And the appropriate and legal reaction to these "sbr related questions" would be "am I being detained" and "where is your ATF badge?"
“Yes, you are being detained, on suspicion of possessing an unregistered short barreled rifle. A federal felony. If you can show me an approved form 1 or 4, we can all be on our way. If not, im going to arrest you, and we can figure it out later.”
You may beat the charge, but you wont beat the ride to jail or the time while i figure out if its a legal gun or not.
So play your silly games, think you can just ride around without the paperwork for your SBR/SBS/MG and no LEO can ask to see those documents because they are “tax documents”. You are wrong and your wake up call will be ugly. Just like all the idiots that wont Register their cars or get drivers licenses and get yanked out of the car after having their windows broken.