I have heard of the "pot metal" stipulation though, but I don't know that it's ever been enforced. I've seen "pot-metal" guns like Jennings, Lorcins, Ravens, etc. for sale at gun shows and of course there are a plethora of quality polymer-framed guns that don't meet the melting point standard.{/QUOTE]
Poly frame guns are explicitly exempted from the 800F test.
Please note that it is is only LICENSED DEALERS that can not sell these guns. Individuals still can own, buy, and possess them. If a Licensed Dealer is selling (or even -displaying-) a Jennings or Lorkin at a gun show, they are putting their license (and their $10,000 bond ... oh ya, really, $10K) at risk.
I have a shipment en-route to me right now from a person that used me for a transfer that is a prohibited gun. Fortunately, I know about it now and can simply refuse it when it arrives. THIS is why I prefer folks contact me first before they send a transfer my way.