You know talking about crimping. I have been playing alot with my chrono lately. I shot some grandslams loaded with 95gr of H1000 and loaded to a COL of 3.65" which is well past the cannelure. I then use the same load crimped at the cannelure loaded to 3.55" . Wow, what a difference it made in pressure.

the long ones shot 3150fps, the short ones crimped got 3320fps. Thats huge.