The part gets pretty hot during the process, and is held at the high temperature for a while... This may be why we do not see very many bolt-action receivers color case-hardened, but instead it shows up more often on single-shots and lever guns.
Mauser uses beautiful color-case hardening on some parts of their bolt guns, but I do not remember seeing it on the receivers.
If somebody says that they can do it, I'd make reeeeealy sure that they know what they are doing, and can prove it.
Edited by charlesb (09/15/15 04:47 PM)
Kind regards, charlesb