Why I think the Satterlee and Audette Ladder Tests Work and Why-- You Decide!

[Veteran]

Just stop there, POI shift and MV are tied because of bullet release timing through barrel vibrations.

The cherry picked declaration by Vaughn is easy to take out of context.
He is not saying that vibrations change velocity, and that is not demonstrated in his book.
He's changed release timing, via changing MV, to cause vertical shifting, supporting one hypothesis about how barrels vibrate in vertical.

You can test this whole notion of vibrations changing MV in 5 minutes at the range to see it fail. One 5 shot group.
Have a buddy Grab/squeeze the barrel and fire through that chrono mid grouping, does MV change? NO
Forget the target, you likely missed it completely, and Vaughn described why.

What is needed in this kind of experiment where you want to see the damping effect of your buddy holding the barrel and looking at muzzle velocity is to also to increase the charge weight as you go......the whole increase in muzzle velocity Harold Vaugn is talking about and the change in POI is due to increasing charge weight. Essentially the OCW method. A better test is to go run the OCW method, and monitor not only POI shift as charge weight goes up, but log velocity at each charge weight and graph it all. I would be interested to know if this shows that velocity flattens and becomes more consistent as charge weight goes up at the same shots where the OCW test finds the smallest groups on the targets.

Just shooting the same ammo with your buddy damping vibrations on all the same ammo is likely to show you nothing.
I agree with that. Thats like putting a barrel tuner on, and just shooting it on the same setting every time. No change.

If you just want to use the same ammo without changing charge weight, start adjusting the tuner, to different settings and log the velocities......there is likely going to be some small velocity change as the barrel goes into tune. But in order to see the magnitude of how the bullet timing of exit from the barrel is impacted by changing the barrel harmonics you are going to have to have some fine quality ammo with ES and SD down in the single digits. Otherwise you will miss it and will not be able to measure it. I believe the magnitude of the velocity changes where the curve flattens or goes down can be very small. Typically 5-10 fps or less. Look at some of the Satterlee curves. Run the Audette test the same way.

What we are talking about here is changing the bullet exit time in milli seconds of mill seconds to get the barrel pointing in the same direction at the same POI each shot. The fps needed to do this can be very small in a "velocity node" window, and then
not happen again until a much higher node on a higher harmonic order. If we just agree to disagree on this that's fine.
I may not be right, but this is what I think in the absence of hard data. I would love to see any work anyone has done or does in the future to plot velocity graphs by shot for increasing charge weights as they shoot Satterlee, Audette ladder, and OCW tests.

The key has to be identical temperature, cooling between shots, and great quality low ES and SD ammo, Same rifle.

What's that famous saying. In God we trust, all others bring data? I'm fine with that. This community either has the data or can
get the data to prove or disprove my hypothesis.....Its what I think, right now. Unproven with hard data, so get some guys together, like the community did for Hammer load data, go out and shoot some Satterlee Curves, Some Audette Ladder tests, some OCW round robins and log velocities. Use great quality ammo with low ES and SD, Let's see what the data says?

I suppose over time, I can do some of this myself since I am the one who's so curious and thinks it is all related.
But, it would be much better as an LRH community project, and have more acceptance one way or the other too.

I am not afraid to say I am wrong if the data says so.

 

[Mikecr]

There are:
Prerequisites;
Primer striking and bullet seating
Tuning;
Powder nodes, barrel nodes, and system nodes

All items can be isolated as separate, even while this affects that, etc.
What we often see from shooting rock stars and thing peddlers are implications of declarations supported, with only limited conditions.
But to save time with it all, do this:
When meeting a new idea, instead of reaching for desired validation, look for the simplest of ANY failed test.
To begin here it seemed like you're looking for validation that things work, while dismissing consideration that they don't (not really).

I don't know how long you've been in this, but I don't see anything done today that is new to past cycles.
OCW is incremental load testing with a goal of forgiveness from powder (a powder node).
OBT is a laughably over-simplified notion of a vibration, with a goal to steer clear of that single vibration (as though they don't sum).
SInewave testing and barrel tunings on target are variations of Audette Ladder testing. It's a sum result, that doesn't need reinventing by every competitor who had a good weekend..
Many others amount to ridiculous shortcuts, with an exception being DOE. That had great potential.

When some day, an intelligent outsider assembles a standard procedure for load calibration, that I'm sure will be sourced from understandings way beyond any of us today, I would be the first to nominate them for a Nobel Prize in Ballistics.
Until then, I see everyone floundering just the same as we ever have.

I am a professional Devil's Advocate, as my occupation centers on it. This can suck I know.
So I am sorry if my inputs hurt progress of your goal.

 

[Veteran]

This explains why I think what I think Mike. Hope you will review it. We can still agree to disagree, but its not only
me that's crazy then......

Barrel Harmonics Are A Lot More Important Than You May Think or Know--Here's Proof

First, I have searched for information for about a year and half on this subject. Some of you may know of something really good I've missed, but the best source I have encountered for information on this topic is Al Harral. Who is Al Harral? Al Harral is a retired guy--but one smart...

www.longrangehunting.com

 

[Mikecr]

I read it, it's common info, nowhere does it imply that barrel vibrations change muzzle velocity.
They don't.

Powder tune, and barrel tune, are different and separate animals.
Ideally they would lay on top of each other but that is often -not the case.
Your best load from a given barrel and powder may not be at your lowest potential ES, nor most forgiving.
You might have to accept compromise in this to have bullets released with the tightest shooting barrel timing.

I say it's a compromise because best barrel timing loads are optimized by range.
And LR hunting requires more than a fixed range accuracy.

 

[Veteran]

I agree that your best groups may not be at your lowest ES, I think that is because of positive compensation which he points out comes from 1 bullet with higher velocity hitting the target at the same spot as a different bullet at a lower velocity. Velocity was different but both hit the same place at a certain range with different flight paths and time of flight.

Although his method looks only at the last 1/2 inch of the barrel and where it is pointing at bullet exit,
I have a very hard time knowing that the bullet can be affected by up to 3 or 4 shock waves in its travel down the barrel before it exits and that the movement in all directions of the barrel during those shocks and vibrations does not cause any pressure or velocity variation or change in bullet friction, is just not possible to me. No, he does not overtly get into this because it may be either too complex to model, or measure or because he has a simpler method that gets 90% there.

No, he does not show us cell to cell pressure and velocity profiles along the bbl over time at various frequencies of vibration. But the videos he shows of undulations in the barrels, tells me at least, that there is action and reaction being imposed on that bullet while it is still in the bbl.

I wish I could ask him.

 

[aschler]

What is needed in this kind of experiment where you want to see the damping effect of your buddy holding the barrel and looking at muzzle velocity is to also to increase the charge weight as you go......the whole increase in muzzle velocity Harold Vaugn is talking about and the change in POI is due to increasing charge weight. Essentially the OCW method. A better test is to go run the OCW method, and monitor not only POI shift as charge weight goes up, but log velocity at each charge weight and graph it all. I would be interested to know if this shows that velocity flattens and becomes more consistent as charge weight goes up at the same shots where the OCW test finds the smallest groups on the targets.

Just shooting the same ammo with your buddy damping vibrations on all the same ammo is likely to show you nothing.
I agree with that. Thats like putting a barrel tuner on, and just shooting it on the same setting every time. No change.

If you just want to use the same ammo without changing charge weight, start adjusting the tuner, to different settings and log the velocities......there is likely going to be some small velocity change as the barrel goes into tune. But in order to see the magnitude of how the bullet timing of exit from the barrel is impacted by changing the barrel harmonics you are going to have to have some fine quality ammo with ES and SD down in the single digits. Otherwise you will miss it and will not be able to measure it. I believe the magnitude of the velocity changes where the curve flattens or goes down can be very small. Typically 5-10 fps or less. Look at some of the Satterlee curves. Run the Audette test the same way.

What we are talking about here is changing the bullet exit time in milli seconds of mill seconds to get the barrel pointing in the same direction at the same POI each shot. The fps needed to do this can be very small in a "velocity node" window, and then
not happen again until a much higher node on a higher harmonic order. If we just agree to disagree on this that's fine.
I may not be right, but this is what I think in the absence of hard data. I would love to see any work anyone has done or does in the future to plot velocity graphs by shot for increasing charge weights as they shoot Satterlee, Audette ladder, and OCW tests.

The key has to be identical temperature, cooling between shots, and great quality low ES and SD ammo, Same rifle.

What's that famous saying. In God we trust, all others bring data? I'm fine with that. This community either has the data or can
get the data to prove or disprove my hypothesis.....Its what I think, right now. Unproven with hard data, so get some guys together, like the community did for Hammer load data, go out and shoot some Satterlee Curves, Some Audette Ladder tests, some OCW round robins and log velocities. Use great quality ammo with low ES and SD, Let's see what the data says?

I suppose over time, I can do some of this myself since I am the one who's so curious and thinks it is all related.
But, it would be much better as an LRH community project, and have more acceptance one way or the other too.

I am not afraid to say I am wrong if the data says so.

Isn't OCW based on the theory a wave is traveling along the length of the barrel? Is so, adjusting a tuner or holding the barrel isn't going to have any effect on this wave which will be traveling at the speed of sound up and down the length of the barrel.

 

[WildRose]

Curious why? Another form of backpressure is friction.
More friction definitely decreases muzzle velocity.

Not necessarily because it also increases pressure which then up to a given point of resistance is going to increase velocity.

 

[WildRose]

Isn't OCW based on the theory a wave is traveling along the length of the barrel? Is so, adjusting a tuner or holding the barrel isn't going to have any effect on this wave which will be traveling at the speed of sound up and down the length of the barrel.

Those waves can be interrupted and/or modified with the "rubber" barrel tuners as well as pressure points between the chamber and end of barrel along the stock. That is why contact with the stock can and often causes serious inconsistencies in your groups.

There are actually two different schools of thought addressing that, free floating either the full length of the barrel or from just in front of the chamber forward, and full length contact bedding.

Very few people will do the full length contact bedding anymore but it used to be one fairly extreme method to to tighten groups when everything else failed.

The accustock was designed with a moveable contact point which was another way of changing those wave harmonics.

 

[aschler]

Those waves can be interrupted and/or modified with the "rubber" barrel tuners as well as pressure points between the chamber and end of barrel along the stock. That is why contact with the stock can and often causes serious inconsistencies in your groups.

There are actually two different schools of thought addressing that, free floating either the full length of the barrel or from just in front of the chamber forward, and full length contact bedding.

Very few people will do the full length contact bedding anymore but it used to be one fairly extreme method to to tighten groups when everything else failed.

The accustock was designed with a moveable contact point which was another way of changing those wave harmonics.

First thing I do when making up a new load is chronograph a ladder and look for two charge weights that have low SDs and a small velocity difference between the two. If there is a charge weight I like I move on to accuracy testing, if not I try a different powder. In that way, I am looking for an optimal charge weight.

I don't understand why this behavior occurs but more often than not it does. Also, looking back at all my data I only saw 1 time out of 28 ladders where the velocity actually dropped and this was within the ES of the two loads so I'm not seeing it to the extreme the OP does. But it also isn't a nice linear or exponential curve like you would expect so there is some stuff going on in that area I admit I don't understand.

Yes, the barrel is vibrating and you can change it. From what I remember about OCW, it says you are not going to see a difference in group size when you change MV based on the the fundamental frequency the barrel would be vibrating at and postulates that a shockwave is produced that travels up and down the barrel changing the bore diameter. What I am saying is the speed that shock wave is traveling up and down the barrel doesn't change. If you change the barrel inertia with a tuner or the effective length of the barrel by fixing it at a point it will change the frequency and wavelength, you could also see some dampening depending on the type of tuner and position/stiffness of the fixed point.

 

[Peter Van Dyke]

Are barrel harmonics predictable? Hypothetically, if supplied with identical cartridges will muzzle aim point be consistent?

 

[WildRose]

Are barrel harmonics predictable? Hypothetically, if supplied with identical cartridges will muzzle aim point be consistent?

According to some pretty good write up's I've seen they are predictable which is why different methods of tuning work. If they were not consistent/predictable none of the tuners would be worth anything because the results of their use would be entirely random.

 

[Veteran]

Are barrel harmonics predictable? Hypothetically, if supplied with identical cartridges will muzzle aim point be consistent?

Read this. You will find they are consistent and predictable.

But if you change ammo, the powder, the bullet, or seating, a screw in the stock is loose, or you change the stock, or hang a magneto speed, muzzle brake, or can on your bbl, they will change.

https://www.longrangehunting.com//barrel-harmonics-are-a-lot-more-important-than-you-may-think-or-know-heres-proof.294317/

 

[WildRose]

Read this. You will find they are consistent and predictable.

But if you change ammo, the powder, the bullet, or seating, a screw in the stock is loose, or you change the stock, or hang a magneto speed, muzzle brake, or can on your bbl, they will change.

https://www.longrangehunting.com//barrel-harmonics-are-a-lot-more-important-than-you-may-think-or-know-heres-proof.294317/

To add, even your fingers contacting the barrel can have a significant effect on the harmonics.

 

[Peter Van Dyke]

Does anyone have any idea what an average POI dispersal might be for quality barrels due to harmonics?