I was looking into case coloring and/or case hardening not all that long ago because I was thinking of buying a gun with that option. From what I found in a lot of searching is that better modern materials and tooling basically did away with the need for it to be done the "old way" (?), so the process has changed to one more along cosmetic lines anymore giving different results that in the past. Many companies or gunsmiths that still do it seem to want to keep their own processes somewhat close to the vest in exactly what they do to an extent, the materials added etc., to keep their certain colors or effects unique I guess. I did read that it will fade or change over time, and exposure to sunlight and use may speed that up some over the years. I'm no expert, but there is info out there online about it, history, current methods, etc., if you want to dig some. I wouldn't know for sure either, but would assume having it done by somebody specializing in it would give a better quality job that may last longer than mass produced factory rifles with it done.