Simply put, use sandpaper no rougher than 400 grit, go over all the bits where any moving part contacts the body at all, and polish the rear bolt, spring guide pin, all the dowels (removing o-rings first) and keep doing this with finer and finer sandpaper till shiny clean, then polish with aluminium polish and wool if you want it to look all chromey
Polish in the direction of the parts movement, and not with too much vigour.
Or read that post below mine..