Okay. It's an NGC Matte Proof 66.
When I bought this coin years ago it was in an old NGC holder that gave you no view of the rims. Dave Bowers wrote an article in which he said that the TPGs had certified a number of Mint State
Buffalo nickels as Proofs. According to Dave the Matte Proofs have a dullish obverse and reverse, but the rims should be as bright as a conventional Proof. I asked NGC about this at a winter FUN luncheon, and they told me that they would re-holder the coin FREE OF CHARGE. If the rim wasn't right, they would compensate me. The coin has the right rim, so here it is.
These coins are always controversial to a point because they are so similar to the business strikes. Many collectors have a hard time spotting them, and it's been said that some of the mintage has been spent over the years because collectors disliked the coins and just said to heck with it. A few heirs may have spent them too not knowing what they were.