I have used the Lee Auto Prime II for about 20 years and find it to be the easiest and fastest tool I have used. Prior to using it I spent about 20 years using the priming arm system on my old Lyman press or a Ram Prime tool. I follow Lee's guidance and only use primers they recommend AND CLEAN THE ENTIRE SYSTEM ABOUT EVERY THOUSAND PRIMERS. Every time I open a carton of primers I spray out the metal parts with brake cleaner and wash the plastic parts. I use a cable tie with the end cut square to push the last of the primers down the feed tube, this is essential or you can jam or catch and flip a primer if it is not all the way in. If you raise the press handle before putting a case in the shell holder you can see the primer and be sure it is not sideways or upside down. I wear glasses and make certain to specify safety type lenses when I get a new set.