I thought that's how UPS and FedEx did it; I'll probably check with the local stores too just to see what they say.
What about USPS? I know they have specifications about shipping rifles unloaded, but I don't know if they have any special regulations for shipping a registered SBR (even if the "SB" part hasn't been done yet). I'd assume it's the same process as shipping a rifle, but the regulations I saw specified 16" barrel or longer. It's currently in carbine configuration so it meets those standards, but I'd rather dodge any legal confusion up front.