Good question for a lawyer.
... a real lawyer. NOT me.
Also, probably dependant upon which state you live in.
In TN, you could probably get in an old-timey crank gatlin as an "antique" or "military memorabilia", something like that.
It just depends.
As far as Jesse Ventura's gun, I wouldn't hold my breath on it. If you don't see it at a gun show, it's probably not legal. And, if you DO see it at a gun show, there's a chance that it's STILL not legal!
