Lee Factory Crimp Die crimps the bullet in place more firmly than any other tool Tests demonstrate that even bullets which have no crimp groove will shoot more accurately A firm crimp improves accuracy because pressure must build to a higher level before the bullet begins to move. This higher start pressure insures a more uniform pressure curve and less velocity variation Features a collet that squeezes the case mouth into the crimping groove for a firm hold Shellholder not included Fits all 7/8"-14 reloading presses Mfg: Lee Precision