[mapsjanhere]

I think he's referring to the internal parts of the action. I would use a fine stone, and only go to wet sandpaper (mounted on a really flat surface, chunk of polished granite sample works great) if you see the stone isn't doing the job because the ridges are too big. Using sand paper free hand it's very easy to round over corners that aren't supposed to be rounded, and having to add shims where none were needed before because you took off too much material to get that machining mark out.