Was doing my usual nightly cruising of GB and spotted this advertised as a M&P Pre 10 from 1947. Price was decent and noticed gentleman lived the next town over from me. So made a deal with him to meet and get an even better price

He bought it many years ago and said he did not realize it had been re-finished and probably not original grips - but appear to be correct ones He said he overpaid but couldn't try to sell it as original, so I got it for a great price. He said the R-S under grips was a refinish indicator? Does this sound right and if so, who puts those markings there - S&W so maybe factory done? He also said that's a 1973 date code showing when it was refinished.
But as a neat piece and a shooter vs a collector piece I'm happy.
Any info. would be appreciated.
Thanks!