[Johnny Peppers]

Jerry,

The link provided by Bill gives a good description of the color casehardening process, and where the carbon comes from. At one time Winchester offered what it called "Extra Finish" casehardening as a step above the regular casehardening. This was an extra cost option on the lever action rifles, and some of these rifles have casehardenig colors that range from bright yellow to cobalt blue. After the casehardening process, the casehardening was given a coat of lacquer to intensify the brilliant colors. The receivers of these Winchesters were made of a very mild steel, and the carbon on the surface was imparted by the packing in the container when it was heated.