With regard to the pewter coins. The biggest question I have had is whether they came Black from the factory. The answer is Yes. At least the 1961 Bear Video "The Oldest Game" clearly shows the coins on Fred and Chucks bows to be black. What made them black? I don't know.
But some of the Bear coins have the Bear letters, and line around the edge not black, acting as highlights. If it was a finish reaction why is the only black part the background on these coins ( and yes the finish is intact and original)? Why aren't the letters and lines black also? It has always appeared to me that the coin was painted and then rubbed to allow the letters and other lines to stand out.
I believe that Bear intended the coins to be Black, because he was aware it was black. If they didn't want them to be black, why would they continue to produce them in that fashion. I don't know how they became black, but I believe it was Bear's intent for them to be black.
Here is another interesting point, the 1961 Grizzlies that I have seen have the Black Pewter coin. They have factory camo. I am assuming that in the case of a camo bow the coins are installed last. Other camo bows support this. My 1965 Factory camo Kodiak has no finish on the coin. I believe this is a huge blow to the oxidation discussion since the coin is black and no finish was ever applied! As a side note it is obvious that finish or whatever was on the coins did not stick to the coins very well.
For those that are sure the coins were not painted, how do you know? If Bill Stewart or Fred Bear says they weren't painted I would trust there words. But, for something that happened 50 years ago it is difficult to be certain of something either way with out first hand knowledge. I am certain that they came from the factory black, whatever the cause.