I hope this makes sense w/o pictures. I took a washing machine motor and plugged it in. As the spindle turns, hold a file against it to make it cone shaped and the size of the caliber you are using. . Put the empty casing on the spindle holding your thumb against the headstamp to hold it on while it is turning. With the other hand using steel wool (0000) put it against the casing (or use Flitz on a rag) and the casing will clean up and look like new. Of course this is good for empty cases only. Something to do on a long winters night.