I recently purchased a nice Model 57 no dash serial number N607145, which, if I'm not mistaken, was manufactured in 1980. I knew it was a good probability that the left grip with the speed loader cutout was not original as I don't believe they were used until 1982. No big deal to me. I did pull the grip off to see if there were any markings on the inside when what I believe is a date stamp of 6 80 on the grip frame caught my eye. Following that is a R-B1. After some internet searching brought up some discussions on this forum, I'm thinking the RB may stand for re-blue. Any thoughts on this? And if that is the case, of course that will leave me to wonder why a revolver manufactured in 1980 would also be re-blued the same year??? Following are pictures of the stampings on the revolver.