Jon;
There are only a few ways a gun can "Go OFF Face". If the standing breech bends or the frame itself stretches then of course this going to put it off safe,
The vast majority og guns I believe go off face through wear in the hinge joint & this is primarily a frictional wear & not the result of shooting. I would guess the hardness of the case would add just a bit to the strength of the action but do not have the equipment to test it. I fully agree the color was secondary in the case hardening process. I am not fully convinced though that adding strength was the primary reason either. Throughout industry, including gunmaking, Case hardening as virtually always been used when a hard wear resistant surface was needed along with a soft Tough Core. If for instance you take a part having a 1/8" thickness & put a .010" thick case on it then you have only hardened 8% of the metal.
I do not truly believe the annealed gun is per se "Unsafe, don't think its going to blow up or anything like that. It will be more subject to wear, for instance streaking down the breech face from contact with the extractors in closing etc.
