Hi, I have a s&w 2nd model .38 da barrel and cylinder. It's actually a first model I think, reissued 1871 patent date. Sn# are clearly 2nd model. Leftover parts I guess. Anyway some of the nickel was missing, very thick plating btw. I put it in my electroplating solution, just vinegar and salt and a piece of nickel and 6 volts. Done this many times to remove nickel. Anyway it removed the nickel, the patent date and the sn#. What the hell happened?