A carbide sizer sizes the cartridge while it is being crimped so every round will positively chamber freely with factory like dependability. The adjusting 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 lenght is not critical so this extra operation takes less time than it would if cases were trimmed and chamfered. 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.