Years back, I got a good deal on a 4 inch nickel model 29-2. The gun was tight and accurate, but the finish looked like a spider web of fine surface scratches.
I have always used Simichrome polish on the aluminum on my motorcycles (works very well), and decided to try it on the model 29. Hand applied for about a half hour while watching TV, the results were amazing. It looked like a different gun, with most all scratches gone.
Obviously, to do so, it had to remove some of the nickel. My suggestion would be to save the abrasive polish for sparing use to remove scratches, and not for normal cleaning.
Polishing / buffing stainless steel with simichrome is another story, and will not harm the gun. With a little elbow grease, you can make a SS gun look nickel plated with this stuff. I did a SS Super Blackhawk this way, and have had several folks at the range notice it, and ask if Ruger was offering the SBH in nickel.
Larry