Model P. That is why you put the vise grips over the full cock notch it acts as a heat sink. You only put the heat on the small spot where you intend to drill. Best bet though if you are concerned with that process is the carbide drills although spotting with a small dremel grinding stone would work also if you don't let it get away from you.
Hawg. Sorry bud you are wrong. The case hardening on Uberti and Pietta is done with cyanide so the colors are different than Colt but they are case hardened for sure.