Doug,
When I'm faced with minor pitting I always err on the side of not taking away metal.
What I do is use a drill with a bronze bristle shotgun brush that is wrapped in 0000 stainless steel wool. I work carefully using ample oil.
In the end, it takes off no metal whatsoever according to a bore diameter or wall thickness gauge. What it does do is seem to remove a lot of patina and corrosion sitting in the pits that are there.
I find that the first rule must be to do no harm. Using the method I describe certainly doesn't cure major problems that require reaming or honing, but it does remarkable clean-up results on guns that actually have much less pitting than appears at first glance. (where it is actually surface corrosion, not deep pits)
