Well, I have done a simular test. I used the exact same pet load with 165gr sierra gamekings and 45gr of Varget. I shot 20 shots with runout less than .003, and shot 20, that were ~.007.

There was a real difference. Average group size of the ones with low runout was 1.2" at 100 yards. Average for the ones with large runout was 1.6". Also noted the flyers was causing the higher number.

Is that worth it? Probably not. But I continue to cull thru the brass.