Barrel whip effect?

[gunsandgunsmithing]

It's not unusual to find a spot that shoots small but is not on top or bottom of the sine wave on target....move the tuner a mark or even less and groups blow up. That's a spike created by the many forces and freqs at play. When good groups form on the top or bottom of the sine pattern AND produce predictable, repeatable group shapes, that's when you're tuned.

 

[gunsandgunsmithing]

This same result can be reproduced by powder charge or with a tuner, btw. It's also why I'm adamant about my tuner test being done exactly as I try to describe. If you wouldn't randomly change powder charge, why would you randomly move a tuner? Until you quantify either change's value on target, it's still random. IOW, break down powder or tuner changes into repeatable, predictable group shapes and poi along the "natural freq shown on the target. Doesn't matter in this case if that's 300hz or 300,000hz. The target won't lie.