The title of this post comes from an identical Google search that I did wondering if it is possible to polish MIM parts. To be fair, that's not really my question. I have polished a whole mess of MIM parts in various semi-autos, but this is about a hammer and trigger from a Smith & Wesson 627 Pro.
I forgot to take a before picture, but the S&W website shows exactly what the hammer and trigger looked like in their factory "color case hardened" appearance. That finish looks good on a blued gun, but it's a personal thing for me that stainless revolvers need stainless hammers and triggers. So the bottom line is that I wanted to polish off the case hardened finish to something more stainless'ish.
Now that's better! I had the Dremel out sharpening my lawnmower blade, and even more surprising I had extra time to kill. The polishing pad, polish, and 30 minutes made a significant difference. My 627 is now pleasing to look at and all is basically right with the world. Apparently you can really go crazy and get a mirror-like shine, but this is exactly what I was looking for. Beyond aesthetics, the face of the trigger is much smoother, which I have a preference for. And although it can't be seen, I polished the engagement surfaces which improved the feel of the action. Let me know what you think in the comments.