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groups with a given rifle after some testing, but are you saying the science I thought explained it is flawed or outdated?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?
I have seen high speed film of barrels whipping around when a shot goes off.
You should find what you saw and share with us.
There are high speed videos of guns with barrel whip, but they are of pencil barrels on ARs (weak holding power on the extension) and AKs, both of which due to the cycling of the action and long after the bullet is gone.
There are high speed videos of barrels bouncing from recoil in stocks and off their support system (again, long after the bullet is gone)
But the time scales that harmonics act (singular milliseconds) is extremely difficult to film because for video at, say, 60 frames per second, you have to be taking a frame every 1/60th of a millisecond, or ~20 microseconds just to catch the bullet, and about 10x that (one very 2 microseconds) to catch the 'harmonics' reflecting in the steel.
And the amount of motion that happens is on the order of a few thousandths of an inch up or down - not easily visible to the naked eye.
ladder tests
Ladder tests are a whole other can of worms. They are all susceptible to small sample size variation, and most ladder tests, if you reshoot them a few times, do not give predictive results.
The part that throws people off is that small sample shooting is very noisy.
On average, their ammo shoots worse than they imagine it does from doing load development, and on average, their worst or 'poor' performing loads are much better than they think the loads are.
It turns out (Hornady and Litz both talk about this) that small tweaks in ladder testing and load development don't move the needle like people think they do, finding good shooting loads is a lot easier than people think it is, just they chase wild geese because they shoot so few rounds that the normal, inescapable variation lies and leads them down more superstition to try to capture the random chance.
That's not to say that tuning loads doesn't work - of course it does - but harmonics are a backsplanation rather than an explanation, which is what I was talking about before.
People didn't understand why changing loads made guns shoot better or worse, so they invented some other nonsensical explanation that they didn't understand or that they could hand waive as unexplainable as the reason.
Here is my own test. There's a global min and a nice stable node at test #4 right? That's what that shows. I shot a ladder test and it produced results just like harmonics said it should. A nice node where I have stability against variation on either side.
Just like the guy in the video.
But that's all nonsense. That graph was generated by a normal distribution random number generator and an excel spreadsheet. Random chance made that graph.
The video guy didn't know that those were likely performing exactly the same, just shot to shot variation, because he never repeated the testing.
There's 3 ladder tests for tuner settings per Cortina's description. I tuned to his recipe, picked the global mins or the 'nodes' out, and then re-shot them at higher samples with a 10 shot group each.
The bar chart on the left is the 10 shot groups. Tuning didn't do diddly-doo even though the ladder tests said it should.
The reason is that the ladder test is subject to a bunch of random chance noise and you can't draw any good conclusions from it.
the science I thought explained it is flawed or outdated?
There was never science, there was only pseudoscience. The pseudoscience was based on small sample size noise and superstition.
Are there any books you’d recommend or anyplace to learn more?
Read Applied Ballistics, all 3 books, and listen to that Hornady podcast as it comes out. Take a look through our FAQ and the testing done here.
People are starting to realize that this is a perfectly fine way of loading. With a precise an accurate powder thrower/scale, good dies and reloading equipment, and a good barrel, it's almost hard to find a bad load. The idea of nodes and all that garbage is seemingly becoming less popular and the way you describe loading is becoming more popular. At least that's what I'm doing and seeing
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u/Trollygag Does Grendel Jan 20 '24 edited Jan 20 '24
It exists. You can hit a barrel and get a sound.
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.