I used stones, wet/dry sandpaper (progressively from 800 grit to 1600 grit), and finally Flitz to take the flats of my Ruger Mark II "slabside" up to a mirror finish.
It looked great for all of about 10 min.
It all started when I used Flitz on the slabs to clean them up some. It left it looking like crap because the metal had never been intended to be polished.
All it did was bring the tool marks out.
I ended up having to *fix* it by taking it up to a mirror finish.
Again, (I assume) the metal had never been intended to be polished all the way up like that, and it's soft enough that it scratches pretty easy.
One itty bitty tiny scratch stands out like a booger, and requires an enormous amount of work to get rid of.