For me, Case Hardening (Color or otherwise), should be based on the type of steel used. If the parts were originally case hardened by the factory, then one can pretty much assume that these parts are made out of a low carbon or case hardening steel.
If the parts are blued, there is a good chance that the parts are made out of med/high carbon (thru hardening) steel.
Generally, what I have found is that if the trigger is one piece, ie..the trigger also acts as the sear, there is a high probability that the part is made out of med/high carbon steel and is thru hardened. If the trigger/sear combination is two pieces.. where the trigger cams against the sear, there is a good possibility that the trigger is case hardened, and the sear is thru hardened. …again I use the term generally…not always.
You should not case harden thru hardening steel. There is a much greater chance of warping, cracking or the steel becoming too brittle.
When Brownells came out with their Color Case Hardening kits, all sorts of folks got into doing Color Case Hardening, many don’t have a clue what they are actually doing to the steel, or how to do it properly. Some of these guys will CCH just about anything.
A good rule of thumb when contemplating getting something CCH, ask if there is anything that they won’t CCH, ask them if they will CCH a frame made out of 4041 or parts made out of 1095. If they become confused by the numbers, or if they say yes…just walk away.
V/R
Mike
