In the US the receiver is the registered part. IF the rec is intakt, regardless of condition, it must be registered - NO exceptions!
Sarge has it exactly. It doesn't matter if it's a rusted up hulk, if it's intact, it's still applicable to the law. No matter how absurd it might look, to Them, a full auto gun is still a gun.
"Much that once was, is lost. For none now live who remember it."
Wow silly that relics are treated like that, the law aside though, it sure is a nice looking one in the OP!!!
My one that I dug up some years ago
When you're wounded and left of Afghanistan's plains,
An' the women come out to cut up what remains,
Jest roll to your rifle an' blow out your brains,
An' go to your Gawd like a soldier." - Rudyard Kipling