Ed I won't argue about case colors fading but I will say this---> I have a lot of L.S. Starret tools in my machine shop. Some of these were my Grandfather's. L.S. Starret case hardend/colored some of their tools like surface gages etc. After over 80 years of daily use by my Grandfather, my Dad, and now me, those colors are still there. They have had sweaty hands, cutting oil, swarf, and you name it on them. At the end of each day they were wiped with a clean rag and put back in the tool chest. Why a gun doesn't keep its colors and my Starret tools do is beyond me. My 1900 Remington has one small speck of its CCH left but you know what? It will stay that way. I kind of like it the way it is.
J.R.B.--
The difference between hardening on your Grandad's tools and vintage guns is simple:......your tools are "THRU CASE HARDENED" AND "GUNS ARE NOT THRU HARDENED, ONLY SURFACE HARDENED".........Big difference J.R.B.....
Basically, "the longer a piece is left in the furnace at temperature, the deeper the hardening penetration"....Tools are thru hardened usually and are also cased at much higher temperatures. Many tools are "oil quenched" not "water quenched".....BTW.....
Best,
