2-piper, the information I wrote about was from the 18th Edition of the Machinist's Handbook. As far as how the "old masters" did it, most handed down until they found what they liked. It's a shame that most of it is gone or kept secret.
There is a good article in "Home Gunsmithing Digest" by Tommy L. Bish, published 1970, that goes into detail on how to case-harden, case-color parts.
As far as you saying they would invest that much time in the process because labor was cheap, I disagree, labor is still expensive, no matter then or now, $.20 /hr. then to $30.00 /hr. now, still relevant.
I know that L.C. Smith's parts were all hand fitted, and their case-hardening-coloring was some of the nicest around. So I cannot believe that that much time was invested in the process. I've never tried to file a case-hardened-colored piece to see if it was truly surfaced hardened. Maybe someone could tell us if they did. David
