Flitz!
I have one that has been professionaly done, and some that I just do myself. Some 629 no dashes look like they have been factory polished, but that's the difference between then and now. Flitz isn't abrasive according to the container, and it is really easy to use. I use it as a part of my cleaning proces on revolvers, especially the cylinders. Stainless will grow cheese if not polished now and again, it does contain aluminum that readily oxidizes. I just bought a 610-2 that looked "OK" until I started to clean it. The man I bought it from said he hadn't fired it in 4 years, and that wasn't all he hadn't done with it. My usually cleaning just got it to where I coud start to see how dirty it really was, a first for me. I guess the third time around things started to clean up. I ended up really puting the elbow grease to the whole gun. The bore was nasty, but the cylinder bores were worse. I ended up going in there with a dremel and some mild polishing compound after scrubbing with what ever I had. She's clean now, and not a blemish on it. There's just something about stainless steel. Flapjack