re: short barrel rifle question

It's a grey area. Many say it's ok to possess a SBR upper(w/o stamp) if you have a registered pistol receiver or if you have no other spare lowers in the vicinity. If you have a SBR upper in your house with a unregistered lower, even if unassembled you could get in a hairy situation. I guess if you wanna cover all your bases order your upper and store it in different location then any non-registered lowers.