In shooting my 8mm Remington Mag I have had un-crimped 200 and 220 gr bullets move in the neck of the cartridges in the magazine from recoil. In one instance the bullet moved far enough to prevent the cartridge from feeding. This was with new sized brass with no neck turning. I use the "factory crimper" on all my loads: 30-06, 308, 8mm mag. Just a touch, barely discernible. Years ago I proved to myself that the crimp improved uniformity. Unexplainable fliers ceased happening when I added the crimp. The "factory crimp" works on bullets with or without cannelure. A roll crimp is used only on bullets with the cannelure.
