Buffalo Nickel Struck From Matte Proof Dies?

1) Any die is capable of a strike like that, if they choose to strike the coin that well.

2) In that day, the dies used to strike Proofs generally went on to serve as Business Strike dies when the Proof run was done. It's nothing extraordinary.

So, yes, the seller could be right but the coin gets to stand on its' own merits. Everybody wants to be the one to get a 1917 Buff certified as a Proof, but nobody has managed yet. There's a hint that Proofs might have been struck of some denomination or another in 1917, but nothing solid in the 98 years since.

I'm no matte proof expert, but I say it's a well struck business strike.

Considering they didn't strike proofs in 1917 there were no proof dies for it to be struck from. Roger Burdette has found documentation that the decision not to strike proofs in 1917 was made in 1916 so there would be no reason to have made proof dies in 1917.