Can some of you machinist explain to me how to polish a collet. I have a sinclair neck turner, and the only way I can use it is to run my cases in a mouth expander. But after running my cases thru my FL die, I have one heck of a time getting my case back out of the expander without pulling the mandrel out. All these are from Sinclair Intl. They suggested a polish the mandrel in a drill. I have tried 300 grit sandpaper, but there has to be a better, faster method to smooth this down. I also would like to polish my collet die from Lee for more neck tension. But I don't seem to be removing any material. I would like to remove .0005" to .001".