I've used Flitz on S&W stainless revolvers with the stock "tumbled" stainless finish, to remove scratches, but you have to be very careful with it! It works too well sometimes! It can create a shiny spot, incompatible with the rest of the revolver, in no time. It can also smooth out the crisp roll marks on a gun, lessening the appeal and probably the value.
You can gingerly use Scotchgard white or gray pads (from an auto parts store) with the Flitz to carefully create that light swirled or tumbled finish. (Do not use Scotchgard green pads; too abrasive).
I would not use Flitz on any gun with a beaded finish, e.g., a 5906, nor would I use it on any aluminum finish (since they are coated with a clear lacquer). Nor would I use it on a "blue" or blackened (melonite or armornite) finish, for fear of wearing it off.
Finally, it is not a bad polish to use -- carefully -- on a bearing surface of a trigger part. It will remove metal, so you have to be very careful, but it can bring those surfaces to a very smooth finish.