Originally Posted by ridge_runner
Technically if the lower receiver wasn't marked as a pistol or receiver on the 4473 you and the dealer filled out, than it can still be considered an SBR.
Technically if the receiver, stripped or otherwise, was transferred as anything but "other" on a 4473, then your 4473 was WRONG.
A receiver, stripped, or otherwise, does not constitute a "rifle" nor does it constitute a "pistol." It is a receiver. You can build it into any configuration you want to. Even if it came as a complete receiver with a butt stock on it, as long as you didn't assemble it as a rifle FIRST, you can build it into a pistol without concern about building an illegal sbr.
The receiver does NOT need to be engraved or marked as a "pistol."