Thanks, Mike. I certainly defer to you as to value -- you know a lot more about it than I do. (And that's good news for SP! )

I tend to lump the RMS and NRMs together, philistine that I am, i.e., any of the 5K+ guns Roy discusses in his seminal article of 1989. I meant that there was only one model (RM/NRM) magnum pre-war, it was in 357, and that all of these had the grooved hammer. There were no other pre-war magnums. Produced by S&W, I s'pose I should add.

How about the RM hammer on ODs though? Now I seem to recall that maybe some of the transitional OD models in the early postwar years had the RM hammers, that perhaps the factory used left over grooved hammers on these... But wait... Maybe that was RM bbls...)

How did RM hammers show up on ODs? That's the question I have now.

(Say, somebody better jump in here quick with accurate info before I totally pollute the knowledge base with misinformation!)