[Aerkuld]

I was reading this earlier and I think the answers were basically on the right track as I understand things. I know that in Georgia at least (and probably everywhere?) a foreigner can legally buy a firearm without being a green card holder if they have a valid hunting license, can demonstrate that they are in the country legally, and if they have proof of being in the USA for a certain period of time - I don't recall but I think its three months. Of course there is nothing to stop them buying one in a face-to-face transaction but, as others have said, a lot of people are very cautious when selling and probably wouldn't sell to someone they didn't know.
Legal gun sales are far more tightly controlled than the media and anti-gun folk would have you believe.