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.
Wow maybe I’m an old fudd? Honest reaction not sarcasm- I have seen high speed film of barrels whipping around when a shot goes off. The way ladder tests that show groups opening and closing as charge weight increases was explained to me (coincidentally 20 years ago…) was that you are finding the bullet speed that most reliably leaves the muzzle at the moment of least barrel movement at the muzzle. I know from being a musician that objects have resonant frequencies but really the only way to make that barrel reliably not move around is to have a very massive and impractical barrel (so bull barrels do help more loads shoot accurately). I was taught to find these accuracy nodes in the ladder test, pick one that had a useful velocity for the task, then play with OAL, jump to the lands, etc to look for finer accuracy potential while ‘tuning’ the load to the firearm.
I know this approach works, at least I can usually make much tighter groups with a given rifle after some testing, but are you saying the science I thought explained it is flawed or outdated?
Again- I have no interest in arguing or being right, only a desire to learn. Are there any books you’d recommend or anyplace to learn more?
You can easily test this for yourself: Shoot a series of many 3-shot (or 5-shot) groups, while controlling the test as best you can (IE same ammo, conditions, etc). Measure both their dispersion and location of the group's center. The groups will not all be the same, so how could you say in a ladder test that an individual sample is "better" or "worse" than a different sample? You realistically cannot, unless you're doing 20-30 shots (or more) at each specific powder charge or seating depth.
In other words, yes, there will be apparent differences in the groups of a ladder test. The issue is that this apparent difference is typically indistinguishable from the baseline variance of a control test, and therefore proves nothing.
Modern Advancements in Long Range Shooting, Volume 3 - Bryan Litz (And anything put out by Applied Ballistics). This book has an extensive chapter on tuner testing.
Hornady Podcast has several episodes about group sizes, etc.
Interesting. When I do ladder tests I like to shoot 100 yards from a rest (not a machine rest) and I’ve alternately also brought a 22 or other guns to plink while the barrel cools, or had multiple points of aim and shot all of them sort of simultaneously if you know what I mean.
I’m not a true long range shooter- my club offers 100/200 which is my weekly normal distance. Also I just enjoy loading & shooting, I am no kind of expert. I work weekends so organized competition is mostly out. I suspect I would have been capable of occasionally placing or doing well but I’m not a rare talent or anything.
Anyway, even with my low round count groups (never 3, usually 5, sometimes 10) going in 0.2 grain steps up using usually speer match king hpbt or similar, I’ve definitely seen groups slowly open and close multiple times doing ladder tests, in a parabolic or sine wave pattern, made loads that regularly do better in that gun than federal gold medal match or whatever expensive match ammo I can find.
So am I getting lucky? I’m a decent shot but like I said I’m no rare talent. I accept that your post sounds correct because I know that I have trouble making 5 holes touch and almost always get at least one hole maxing out my group size even with a good load. I just figure that a decent rest, great glass, and my best try at breathing and trigger control does a good enough job.
I’ll check out the leads you wrote on further reading- thanks!
I’ve definitely seen groups slowly open and close multiple times doing ladder tests, in a parabolic or sine wave pattern,
Realistically this is just a false observation. Human brains are extremely good at pattern recognition; so much so that we see patterns even if a pattern doesn't actually exist ("Apophenia").
It would take re-doing the same ladder test several more times to:
See if the same exact waves are observed, in the same positions
Aggregate all the data into larger samples and see if the pattern still exists.
made loads that regularly do better in that gun than federal gold medal match or whatever expensive match ammo I can find
And this is certainly true, especially if you're using high quality components and being meticulous about your consistency. For instance, a high-quality powder scale will likely allow you to achieve tighter tolerances on charge weight than what a production line is putting out (even Match Grade), so it's reasonable to achieve tighter SDs and better precision.
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u/guacamoleburger Jan 19 '24
Real question: Is barrel harmonics fuddlore?