I'll usually start out with 320 or 600 grit wet/dry sand paper (for the rough areas only) . I would NOT go any coarser on a bolt,(because it SHOULD be pretty much finished,and we don't want to scratch it).BUT, if the bolt, and or guides, are allready smooth,(no damage,just in need of polishing),I use a Dremel with a dense pad and rubbing or polishing compound. Don't think that because it's just a pad, that it can't damage the surface, but it is lot's more forgiving than sand paper,files,etc. Just take it slow and use some common sense,and don't get impatient. If you've NEVER done this type of thing, I'd suggest practicing on a piece of scrap metal,or somthing to get the "feel" of it. There are several other tools an procedures that can be used, ie., pencil erasers, polishing stones,soft polishing pads,etc. I'm just giving information about the way I like to do the job.