I think that S&Ws coloring treatment on their hammers and triggers these days is cosmetic rather than true color case hardening Heck, most of them are MIM parts now, I'm not sure that material can be color case hardened.
I have a 327NG that recently had the hammer bobbed and some action work. The 'smith bead blasted and blued the trigger and hammer, they came out looking nice and no worries about strength. I think the coloring is better now, too.
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