Dragline's got it. I found a PPK in stainless for a rock bottom price because of a mean looking scratch. In less than half an hour the scratch was gone! The green pad is a friend to stainless. If used for a satin finish, post polishing isn't required.
For a brushed finish I start with the green pad and finish with the less abrasive light gray which gives it more of a satin look. If going for a high polished look I use very fine grit wet-dry before actually polishing. It takes any graininess out of the metal and gives you that flat mirror finish as opposed to just being shiny. I have a post a while ago I can dig up where I go into more detail if anyone wants it.
Here is one of my older posts
The green scotcbrite pad is a little more abrasive than I like to use to get a nice satin type brushed finish. Check out an auto supply store, and if you want a satin typed brushed finish get the light gray 3M Scotchbrite pad, these things are basically synthetic steel wool. You could even pick up the white scotchbrite pad to give it its final brushing on the finish after you used the gray. If you want a flat satin type finish without bead blasting you can use different grits of wet-dry sand paper. If you wana go this route I suggest picking up 1500, 2000, and 2500 grit wet-dry, use the wet-dray sandpaper with a little bit of gun oil. When using either the scotchbrite pads or sandpaper cut out small wood blocks to wrap the pieces of scotchbrite pad or sandpaper around, and I mean small as in maybe a block the size of a zippo lighter and one half that size. This will help you apply even pressure with each stroke giving you a more uniform finish. You want to try to keep long even strokes in the same direction which the wood blocks also help you achieve. It may take alot of trial and error but you will eventually achieve a finish you find desirable with a little experimentation. If the brush marks in the stainless don't look as smooth as you want a very quick, and I mean pretty quick, wipe down with mothers mag polish or flitz might take some of the edge off. Too much polishing though and you will just ruin all the work you did and will have to rebrush the stainless.
If you want a mirror polished finish you could always just polish the heck out of it with mothers mag polish or flitz, but that alone will not give you a flat mirror finish. You want to use wet-dry to take the graininess out of the metal before you use the polishing compound. I suggest starting with 1500, then finishing off with the 2000, or 2500 wet dry. Again, using woodblocks will make the job alot easier and give you more of a uniformed finish throughout the gun. A little dab of gun oil on the wet-dry helps as you go along. You want to periodically test areas by polishing with a polishing compound and checking for graininess so you know when to stop using the wet-dry and when to start polishing. It's time consuming but once finished you will have such a flat even mirror finish that it looks like nickel plating.
The 1500+ wet dry grits are very mildly abrasive. When working by hand you really don't have to worry about taking too much material off, your hand will cramp up before you could even achieve it.
Kind of a relief, like the first scratch in a new car!
