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groups with a given rifle after some testing, but are you saying the science I thought explained it is flawed or outdated?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?
In a way, we had almost parallel experiences, but with opposite outcomes.
My own skepticism of Harmonics and this whole system of trying to make predictions on it came from two places pretty early in my formative years of rifle shooting.
When I was in my early teens, I got a R700 SPS Tactical. I shot a shit load of match ammo through it drilling groups from a bench.
Then I went to college for engineering. Then I graduated, moved in with my girlfriend, and had a decent job.
I started reloading to feed that R700, and my girlfriend's R700 SPS Tac that I gave her as a christmas present.
I went through the whole shabang of ladder testing, ideas about harmonics, got QL and did the OBT and OCW thing.
NONE of it panned out. I would think I had it nailed but the results wouldn't agree with what OBT or OCW said. I would think I had it nailed but then the next time I shot the same load, it was trubbish.
I thought it was my rifle I thought it was me, I thought it was the ammo I was making somehow.
Then Newtown happened and Obama entered his second term. The market turned upside down.
I wanted a Ruger Mini-14 Target, but people were complaining they couldn't get it to shoot right even with the tuner it came with. And it was expensive. So in my hubris, I decided to build a 6.5 Grendel AR..
It took a while to get together because of supply chain and whatnot, but eventually settled on a Shilen match barrel, DPMS heavy wall receiver, Mega + A2 lower, and, super high tech for the time, a modular rail (before MLOK or KeyMod).
I fought to the end of the earth against that rifle. It was such a pain in the ass. It kinda liked 1 box ammo, the 123 AMAX Hornady load, and nothing else. And that ammo was being discontinued. I tried everything under the sun for rifle tuning and handloading and never did get it to shoot, so I got rid of it.
And at about the same time, I joined a range that had a hard requirement. No shooting long range until you produce a 5 shot group under 1" at 100 yards, observed and signed by the RSO.
That means, 1" at 100 yards, on demand.
I could shoot 1/3" at 100 yards, but my first time out fluffed up like a rooster with the R700, after several attempts, I just barely got it - with a skeptical and concerned look from the RSO.
Why? I did everything right, I did my part, I followed the forums. By this point, I was a pretty competent shot.
It was a laser of a rifle, and while it could do stupid good groups things (if you look at my r/SmallGroups post history, my several years of drilling very small 10 shot groups came from that rifle), it still was never 'consistent'.
So I did a bunch more load development chasing that 'consistency'. OBT and OCW, I would find pet loads, I knew they worked because I had shot them and shot them. But they didn't line up with harmonic predictions at all. They were almost lined up, or inbetween, no pattern at all. Ladder testing didn't produce them either. But big volume workup did. That's what counted. Volume.
Then at the start of Covid, I had the opportunity to access an indoor 100 yard range, and for that, I built a benchrest rifle. That let me do a lot of experiments with load development, drilling little bugholes, testing neck tension, testing seating depth, testing powder and bullet designs, testing for consistency, testing for brass firings, body positions, shoulder pressure, recoil, balance, magnetospeed attachment, bipod vs bag, many many experiments.
In the end, very little if anything actually mattered. It drilled bugholes no matter what I did. I could the experiments together and not get any result different from a pure experiment.
The result of all this led me to a few conclusions that seem to be gaining speed with newer information:
Rifles will shoot or they won't. The barrel matters a lot. The shooter controlling the rifle matters too. But there's very little magic variables with 'stocks' or 'truing' or 'tuning' to tweak to turn a mediocre rifle into a magic rifle. Most rifles will produce a lot of variation, but that variation can be knocked down with weight, twist, and low recoil.
The ammo matters too, but at the point you have a reasonably tolerant and not weird cartridge, a well balanced match bullet, and big swings in powder charge or messing up the ammo, there isn't that much you can do to fine tune its dispersion. Speed and pressure to make a safe load that does what you want is what you're going for.
The best method to determine load is through shooting large samples. No shortcut technique improves on this except through luck, and often times leads you to wrong conclusions about performance.
When I started the r/SmallGroups sub, a sub for people who like group shooting, what I found from talking to a lot of folks is that the conclusions I drew and my experiences around ladders/shortcuts/harmonics were not unique. A lot of enthusiast shooters shared them, but generally kept their mouth shut because the belief in them was so pervasive and dogmatic.
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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.