The Lee Carbide Factory Crimp Die crimps the bullet in place more firmly than any other tool. It is impossible to buckle the case as with regular roll crimp dies. Trim length is not critical. Tests demonstrate that even bullets which have no cannelure will shoot more accurately if crimped in place with the Lee Factory Crimp Die.
A carbide sizer sizes the cartridge while it is being crimped so every round will positvely chamber freely with factory like dependability. The adjustig screw quickly and easily sets the desired amount of crimp. It is impossible to buckle the case as with a conventional bullet seating die. Trim length is not critical so this extra operation takes less time than it would if cases were trimmed and chamfered. Revolver dies roll crimp with no limit as to the amount. A perfect taper crimp is applied to auto-loader rounds. The crimper cannot be misadjusted to make a case mouth too small to properly head-space. A firm crimp is essential for dependable and accurate ammunition. It eliminates the problems of poor ignition of slow burning magnum powders.
Factory ammunition is often more accurate and better able to withstand rough handling because the bullet is firmly crimped in place. 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. Even powder selection is less critical. Until now, handloaders seated the bullet to touch the rifling to achieve similar results. This is not always possible nor desirable.