I'm curious how the dealer tested the coins for silver content. Just for your information, I would question the silver content in these pieces. I have seen several fakes that were not silver. I have never seen an obvious fake that was made of silver but that doesn't mean that they don't exist. I am not saying that your coins are fake but in my opinion they are highly suspect.
Well he did something I was later told by a different dealer I should never allow someone to do because of degrading the coin. A scratch test. He can't tell me the exact content without sending it to be graded. I guess they would use something like specific gravity to determine this? But he told me he could verify they contained silver. He offered me $250 for the four Fatman coins