To shape, I used a fine dremmel sanding drum.
To smooth, I used abrasive prep pads on a drill. Dremmel also makes abrasive buffs,
but I have a bunch of drill mount pads that I got cheap, so I saved the dremmel buffs for tighter quarters work in the future.
To polish, I used the dremmel, with wool pads & red polishing compound.
I only addressed the areas that move against the shells & hammer as the bolt rotates, extracts & feeds & the carrier re-cocks the hammer.
I did not remove as much steel as some do, due to the fact that I fire a lot of 3" magnum & don't