How deep are these scratches? And what is the original finish on your revolver?
If it is a regular, stainless S&W, with just some light scuffing or scratches, I recommend Simichrome polish (link:
Buy Happich Simichrome Polish, only $7.99) which is a paste made in Germany, and available at many motorcycle dealers. It is superb, far better than any other product I've ever used for polishing most metals, including chrome, stainless steel, and aluminum. (And in almost 40 years of motorcycling, I've used them all!) It's easy to use, and a little goes a long way.
I use it on my various stainless handguns, and it does a great job of cleaning them up and brightening them. The only caveat I would offer is that you will have to use it on the entire gun; if you polish only a small area that section will stick out like a sore thumb.
If your revolver has a brushed or bead-blasted stainless finish, Simichrome will remove the scratches, but the finish will be affected too. I can't speak from experience about brushed finishes, but I've polished scratches on a bead-blasted revolver, and then had it re-blasted, and it looks fine.
Hope this helps...good luck!