So, I really want a Colt Commando style rifle, but have a question about the legal part of it. I know SBRs are not allowed in WA state (where my parents live). If I get my stamp, for the only lower that I have, which right now had a 16" upper on it, can I go back and forth between the uppers, and take it into WA when I have the 16" upper on it? Or since it is then "registered", will it come up that it is an SBR if the numbers are ran, therefore making it illegal? I don't want to be limited on where I can shoot the gun in even a normal configuration.