There’s a company in FL: Vintage Industries that make very good repo plastic buttplates, grip caps & grips.
About 7-8 years ago I had them make some custom hard rubber grips for a Colt SAA that I was restoring, the gun has special ordered hard rubber grips, Vintage reproduced them exactly.
Vintage industrys products are very well made, almost exact copies of the originals…except that they are cast, during the casitng process the mixture gets air bubbles it. This is not visable in the finished product, but if you have to grind/fit it down for a better fit you may expose these voids, which are hard to hide.
Mike Hunter
Hunter Restorations