I noticed on some of the published tests, that the pressure spike as the bullet leaves the barrel of this caliber can be almost as high as when the bullet starts when using slow powder like the RL25, and Retumbo, and H870. But that pressure spike is smaller and more predictable when using IMR4350, and IMR7878, and even RL22. I have seen simular results you see, but lose alot of velocity. I was getting almost 3400fps with 180gr nosler partition with RL25, but only got accuracy with 88gr RL22 and at less than 3100fps. Having a heavy barrel on my gun helps this whip.

If people would start loading with faster powder, I bet alot of this finickyness would go away. But then we might as well just shoot a 300win mag.