As someone in sales, the only question that comes to my mind is "Cash, check, or charge?"
Federal law requires all FFL gun dealers to report multiple sales of firearms made by a purchaser in a 30 day span. These purchases should have been reported and the AFTE agency would have checked with the dealer and on the purchasers. This dealer has no doubt been charged under federal law and prosecuted. Existing gun laws pretty much work and need no supplementation.