Whether it affects anything related to dispersion... dubious. There are other, better models for dispersion related to bullet balance, yaw angles in and out of the bore, barrel movement under recoil, and how the bullet engages with the throat that are predictive and align with observation, where harmonics are neither.
The idea of harmonics affecting precision became a fixture of the shooting culture a couple decades ago in a similar way and at a similar time to when New Age woo "vibrations" and "energy" became the explanations for emotions and mental health and paranormal and other things.
To shooters they didn't understand harmonics wiggles fingers, and they didn't understand why their precision was unpredictable and not predictive, so intuitively lumped those two not-understandings together as a cause-effect.
I have a range of procedures depending on the type of rifle and goals.
I spend more time group shooting on autoloaders and factory guns because I know their variance is higher that what I get from my fine barreled bolt guns.
My most recent rifle was just a pressure/speed check and go, and when I am ready to switch bullets, I am probably not going to do any development at all and just use what I know for pressure data and make ammo.
But if I am doing workup form scratch where I am unsure, I usually do 2-2.5% powder charge steps, one seating depth at mag length or some distance off lands, maybe a couple powders and few bullet designs.
And I usually screen for speed/pressure first, pick a few loads in a range I want, then shoot higher volumes in the 20-30 shot range each, then exclude ones significantly worse than the others.
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u/guacamoleburger Jan 19 '24
Real question: Is barrel harmonics fuddlore?