Perhaps the OP is talking Case-Hardened?
The Uberti has beautiful case hardened guns on there web page.
if that is the case I think it is possible to do on a stainless bu it will be more work for the person applying it and thus more money.
Shot placement is everything! I would rather take a round of 50BMG to the foot than a 22short to the base of the skull.
all 21 of my guns are 45/70 govt 357 mag, 22 or 12 ga... I believe in keeping it simple