Hi Flatsguide,
According to Keith Neal, the first gunmaker in England to intentionally produce case colors or preserve those that happened by chance, was William Bailes in the late 1760s. Case colors do not appear to be common on English guns until late in the 18th century. Consequently, case colors probably are not appropriate for the period of gun Chamber's rifle represents if you want to be HC. Simple case hardening without producing colors was of course common and was a very ancient process for hardening the surfaces of iron parts. It probably needs saying first, that case hardening any parts of a Chambers lock probably voids the warrantee. Regardless, I case harden all of my lock plates and flintcocks. That prevents the flintcock from peening the bolster of the lock plate. I also case harden the frizzen. I do that because I anneal the frizzen, which makes it much easier to clean up and polish (and engrave if desired). Then I case harden it. Although I cannot explain why, my case hardened frizzens simply spark better than those hardened by any of the manufacturers. I also case harden the hook and tang breech and any other steel or iron parts that are likely to wear or be exposed to rust. A polished hardened surface is quite rust resistant. The exceptions are the trigger guard and butt plate. I am concerned about warping and misshaping them during hardening. Unless I can block them with thicker steel, I avoid hardening them.
dave
