If you reload various for various bullet diameter cartridges and use the Lee case trimmer tool on your brass, you may have a tool for doing a crown already. Here is a sticky from Surplus rifle forum, gunsmithing section. This method of doing a crown is almost laughable, but I've had good success with it. Not something I'd highly recommend or endorse, but if you need a quick fix for a rifle you don't want to put any money into, certainly worth a try.
