Re: m-2 carbine
Where are they for sale? If in a gun store, is the owner a Class 3 dealer? If not, he cannot legally deal in automatic weapons, but that is his problem. If he is, then it is a good bet the guns are legally registered and can be transferred on a Form 4.
If for sale by a private individual, run, do not walk, away from the whole thing. BATFE has been known to try "stings" involving selling auto weapons to people, then arresting them for possession of same. It is against the rules to do that kind of thing, but not all cops play by the rules.