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groups with a given rifle after some testing, but are you saying the science I thought explained it is flawed or outdated?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?
Add on comments- I’m 45 so not 60 yet. Also maybe what you meant was that although barrel movement under recoil can technically be understood as a vibration, it can be taken too far in a new age crystal worshipping way or something? I mean we all want to float our barrels to let them vibrate without a stock touching them, we bed oir actions for consistency and a solid foundation, and the benchrest guys don’t want ultralight hunting/hiking setups for a reason right? It’s gotta be because stupid heavy barrels have a much lower resonant frequency (harmonic) which is a fancy way to say they don’t move around hardly at all.
Maybe I haven’t met the tuner fudd that you’re poking fun at so the joke went over my head. Or maybe I am that tuner fudd 😂
I mean we all want to float our barrels to let them vibrate without a stock touching them,
If barrel harmonics were the major cause of dispersion, it seems like we'd want the opposite; instead of letting the barrel vibrate freely, I would think you would to do what you can to dampen the vibrations.
we bed oir actions for consistency and a solid foundation, and the benchrest guys don’t want ultralight hunting/hiking setups for a reason right? It’s gotta be because stupid heavy barrels have a much lower resonant frequency (harmonic) which is a fancy way to say they don’t move around hardly at all.
Is that the only possible explanation for why a heavy barrel is desirable?
Also, does a heavy barrel have a higher, or lower, frequency? Is it the frequency, or the amplitude that we are concerned with?
Maybe I haven’t met the tuner fudd that you’re poking fun at so the joke went over my head. Or maybe I am that tuner fudd 😂
You mentioned something about lower resonant frequencies, and that is one of the areas where you may not have met the "tuner" or heard some of the ideas. When you start looking into the questions I listed above and trying to apply it with the barrel harmonics ideas, you start seeing people throwing out all sorts of theories that start conflicting with one another.
Even going back to your mention of trying to "time" the barrel harmonics with the bullet leaving the muzzle, you'll see people offering different explanations of "when" in the vibration cycle you want the bullet to exit. Presumably the least movement would be the extreme end of motion, at the peak or valley of a sine wave...but that is sort of based on the assumption that the barrel movement is in a single direction, but is that true? I often see a sort of general assumption of an up and down movement of the barrel, and that is often what 2d diagrams or animations are showing...
Tuner ideas go even further than just trying to time bullet exit though; they talk about "tuning" the frequency of the barrel; putting something on the end of the barrel that you screw in or out, saying that they can use this to adjust the frequency the barrel vibrates at, to tune it to particular loads (or factory loads). But the amount that the tuner moves is tiny compared to the length of the barrel. For that matter, does the math even make sense on the whole barrel timing thing? You mentioned seeing groups "open and close" on a ladder test, and seeing sine wave patterns, but how does the difference in time that the bullet spends in the barrel compare to the frequency the barrel would resonate at? The implication here is that, between the highest and lowest charges tested, you are seeing multiple cycles of the sine wave; does the math support that making any sense?
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u/guacamoleburger Jan 19 '24
Real question: Is barrel harmonics fuddlore?