Years ago some guy bought a couple of surplus crates from an auction at Hill AFB. Labelled machine parts. Inside were 2 brand new M2 machine guns still in cosmoline. After a brief consideration he took them back. Lol.
I will never understand that.
If that guy had a pricey lawyer on retainer, he might have been able to put the Deuces in some sort of escrow situation, and gotten the paperwork through to take legal possession, but it would probably take years and many thousands of dollars. It would have at least been as likely that he'd have years of litigation invested and end up meeting the wrong judge who just said "nope" and confiscated the weapons without compensation.
If he took one to the range, even if it were a private range, it would get a heap of attention. Trying to get ammo could get a heap of attention. Attempting to offload, even to a private collector... attention of the worst kind. I don't necessarily agree with the rules, but they are what they are. What's the value in having a firearm that would draw that much attention if you attempt to use it or sell it?