Lee 7.7 JAPANESE 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.Specifications and Features: Crimps bullet in place more firmly than any other tool Impossible to buckle case Trim length is not critical Bullets without cannelure shoot more accurately with the factory crimp die