I have worked for Doug Turnbull for the past 6 years, so to say that I have seen a few cch guns would be an understatement.

I believe that UV rays can be as damaging to a finish as any normal wear from use. I also believe that the retention of finish is to some degree dependant upon the metalurgical composition of the piece in question.

I have had the opportunity to examine thousands of original firearms in varying conditions ranging from near mint to looking like a sewer pipe. In the course of a day, there are times which I have to determine the original finish on a firearm. Even those that are color case hardened are sometimes extremely difficult to tell because even the internal surfaces have faded considerably.  This is what makes me believe the metal composition has a lot to do with retention of color or finish.

If you look at any original firearm which has been either charcoal blued or rust blued you will be able to see on the better preserved examples (not a rust bucket) that UV rays will effectively fade the finish in an even manner compared to the unaffected areas which remain protected by wood, mag tubes, etc.

You will also see on some charcoal blued firearms, what appears to be finish flaking off. This also leads me to believe that the metalurgical makeup has more to do with finish condition than we may think.

Both charcoal bluing and color case hardening are finishes which are a by-product of properly applied heat. I will not go into details about the process, so please don't ask. The color achieved in CCH is a by-product of the process which again points to the metalurgical composition of the piece in question.

We do apply a protective coat of varnish or laquer to our CCH parts which help to protect them from fading, enhances the colors and maybe helps with UV rays.

I guess what this all means is we need a metallurgist with plenty of time to figure it all out for us.

I hope I have been of some help to those who were asking.

Jesse