Miller,
Dr. Gaddy recommended Doug Turnbull for color caseing martensitic steel framed guns. Also, there's a gunsmith named Bachelder that does traditional case colors on Parker Repros, although I'm not sure if he does the process or sends it out.
On martensitic steels being too hard at their max hardness, I would agree when discussing gun frames. However, there are alloys that have high shock resistance at very high hardness. With the RBL guns, CSM chose to machine them in their ready to use hardness, which I believe was in the mid thirties RC, not all that hard to machine and still at traditional modern gun hardness.
