I've been using two, one large, one small, of the older 'round tray' Lee primer tools since the late Seventies. I also have a couple of the earlier single primer tools. Mostly they have been used with CCi or Winchester primers as Federals don't seem to be commonly stocked locally. I've had no problems, but have read about them. My Dad was a machinist and he convinced me it would be prudent to wear safety glasses a long time ago.