To smooth actions and the like I use a shaped oak stick backing cloth backed abrasive papers(emory cloth). I buy some from the local hardware store, the rest from an abrasive manufacturer. They can supply the extremely fine, longer wearing ceramic sheets. These don't cut better but last much longer than the silicon and aluminum oxide stuff. Be cautious as if the piece is too rough removing the machine marks may leave too much tolerance(slop!) between the parts. This can be counter productive!! All that's needed is to knock down the high spots and the worst of the rough spots. If the parts move freely, smoothly without the roughness, stop. Resist the urge to bring the parts to a shine.. Shaping the backer stick helps keep the curves and flats the same and keeps them straight! On the outside I always used the same materials and rubber backers of differing shapes to match the needed contours supplimented my sticks. I've been toying with the idea of stones. They are the traditional way to smooth the outside of an action but I've not yet used them. They do however come highly reccommended.. Perhaps the M48 in the basement???