3M sells these abrasive pads. coarse,medium,fine and ultra fine.You can get themiddle 3 at either home depot. The coarse is usually brown in color,the medium is green in color,and the fine is light gray almost silver in color.Thing you get one pad of each grade in a package. Or check Enco online catalog. They have a few more grits like ultra fine listed.But a pack of each grit and go from there. But remember these are abrasive pads they will take off metal. There are also different grits of silicon carbide wet and dry paper. Think it starts off around 180,220,240,300,400,600,1000 and a few grades above that.Completely disassemble the revolver to avoid getting any abrasive on the parts. This is before useing either of the two abrasives previously mentioned. The thing thing you can try is a wire wheel that has fine very thin wires on it. Brownells probably sells it. I have one in my shop and have only used it sparingly on rifle parts. My polisher/buffing machine is set up on a stand that is about 30-32" high.
I have a bad back and cannot stand for long periods of time. The stand was made from an old typewriter table that has wheels and a cute gizmo that allows the table to sit on the floor or be wheeled around. Only problem if I sit for long periods of time then my legs start hurting. If you decide to use the wire wheel make sure you are wearing either a full face shield or some type of goggles. I don't know by what method S&W uses for their satin brush finish on their stainless steel guns. But one of those three should help. Frank