Why do we ignore the horizontal?

[Hondo64d]

Help me out here. In every description of the various versions of ladder and OCW load development methods I have seen, conventional wisdom says to ignore any horizontal distribution and attribute it to wind. We all know barrels oscillate upon firing but what law of physics makes them only oscillate in the vertical axis? Why don't they oscillate in the horizontal axis too? Or in a combination of vertical and horizontal axis? And, if that is the case, why are we ignoring the horizontal dispersion in ladder and OCW type load development?

Thanks,

John

 

[FearNoWind]

I focus on the vertical because, in theory, the oscillations are cemetrical. That is, the distance of the outer edge of the oscillation arc from center should be relatively the same throughout the oscillation period. Depending of MV, the round registers on target at a slightly different position of the oscillation arc with each shot. Because there are more atmospheric fluctuations affecting horizontal than there are affecting vertical, it's the vertical dispersion that I use as a basis for determine the accuracy of the load.
Now all that may or may not have merit. But it's worked for me for fifty years and I'm too old to change my ways.

 

[Rack]

Precision Shooting Magazine - March- 2005 (Vol. 52 - No. 11)
This may be helpful also.

 

[FearNoWind]

Precision Shooting Magazine - March- 2005 (Vol. 52 - No. 11)
This may be helpful also.

With all due respect to Mr. Calfee, I disagree with is assessment of barrel dynamics.
His diagrams would have us believe that the barrel vibrations are linear from chamber to muzzle producing a vertical pattern of fire only.
That's just not correct INO.

https://www.google.com/search?q=rif...hUL4mMKHVACCjQQ_AUICSgD#imgrc=5qS-69YN8zp8eM:

https://www.youtube.com/watch?v=HGivoWD9OvQ

 

[Rack]

That was a good video . I wonder if there's any better ones out there maybe longer barrels and different contour barrels .

 

[BountyHunter]

With all due respect to Mr. Calfee, I disagree with is assessment of barrel dynamics.
His diagrams would have us believe that the barrel vibrations are linear from chamber to muzzle producing a vertical pattern of fire only.
That's just not correct INO.

https://www.google.com/search?q=rif...hUL4mMKHVACCjQQ_AUICSgD#imgrc=5qS-69YN8zp8eM:

https://www.youtube.com/watch?v=HGivoWD9OvQ

What does a video of an AK-74 with a muzzle brake offset at 45 degrees to deliberately distort the standard recoil lift pattern have to do with horizontal or vertical barrel vibrations? Interesting but not relative!

 

[rcoody]

Here is an interesting link on barrel harmonics and the use of tuners on centerfire rifles

http://www.bostromgunsmithing.com/ImprovedRifleAccuracy.pdf

 

[Rack]

In the video I think I can see barrel vibration

 

[FearNoWind]

What does a video of an AK-74 with a muzzle brake offset at 45 degrees to deliberately distort the standard recoil lift pattern have to do with horizontal or vertical barrel vibrations? Interesting but not relative!

AK muzzle brake offset notwithstanding, the video's relevancy is in the observable orbital movement of the muzzle. That movement is independent of the the AK's muzzle rise that affects it in full auto operation. Admittedly it is not the best video example but it's the best I could find - the pictorial representation of barrel whip is intended to provide the static imagery to support the argument. With or without Google, it ain't a perfect world.

 

[Deleted member 46119]

Best description of barrel dynamics I've ever read.

So

In complete agreement, I want to add "physics is physics" you can argue with physics, however, unless you discover a new "law" of physics, you won't win.

We "see" the vertical flex much more but the horizontal/orbital is there.

I focus on the vertical because, in theory, the oscillations are cemetrical. That is, the distance of the outer edge of the oscillation arc from center should be relatively the same throughout the oscillation period. Depending of MV, the round registers on target at a slightly different position of the oscillation arc with each shot. Because there are more atmospheric fluctuations affecting horizontal than there are affecting vertical, it's the vertical dispersion that I use as a basis for determine the accuracy of the load.
Now all that may or may not have merit. But it's worked for me for fifty years and I'm too old to change my ways.

 

[rcoody]

here is one man's thoughts


THEORY


There are two independent types of barrel vibrations.

The
pressure inside the barrel causing it to expand and contract in a



harmonically defined fashion (much like the string on a violin vibrates when it is

plucked) as it moves along the barrel causes the first type of vibration



. When the


bullet leaves the muzzle when it is at its smallest diameter, accuracy is improved. When

the muzzle has expanded and is larger than the minimum, it acts like a bad crown with

the bullet smaller than the bore. Formulas to calculate
Optimum Barrel Time are


provided in the appendix. This vibration mode depends on only barrel length. With the

use of the
Quick Load and Pressure Trace products barrel times can be estimated.



The
second and most significant type of vibration type is the bending mode of


the barrel. Think of clamping a steel ruler to a bench and then bending and releasing the

free end. The ruler will vibrate based on its characteristics and the force applied to start

the vibrations. A gun barrel functions in the same, but much more complicated way.

In the case of our ruler one can write a differential equation of motion to describe

the motion, velocity and acceleration of any point on the ruler. To do this for the rifle

barrel is far more complicated.

Let's consider the series of events from the time the trigger is pulled until the

bullet leaves the muzzle. Each of the following events happens at a small, millisecond

time lag after the previous event.

a. The trigger is pulled to release the sear

b. The sear releases the firing pin

c. The firing pin moves forward, striking the primer

d. The primer and cartridge are driven forward

e. The primer ignites causing it to move rearwards, striking the bolt face

f. The powder begins to burn and causes the bullet to move forward

g. The bullet strikes the rifling and begins to spin

4

h. The action and barrel moves rearward in recoil until the recoil lug is stopped

by the stock

i. The entire rifle recoils

The list could go on, but the reader should get the point. Each of the events can be

described with a differential equation of motion, each spaced slightly different in time.

All of the differential equations need to be simultaneously solved to get a picture of the

barrel vibration. Solving the equations is not important, but knowing they exist is. What

the shooter sees is the sum of all these. You might ask why this is important. We will try

to answer that question shortly.

The barrel will vibrate with a number of modes or harmonics. Simply put, each

successive mode (harmonic) will cross the centerline (the nodal point) of the barrel one

more time than the previous mode (harmonic) and be at a higher frequency. For example

if the second mode (harmonic) were 445 cps the third mode might be 1,246 cps. As the

harmonics increase, the final crossing point gets closer to the muzzle. A good example of

this can be found on
Varmint Al's web site www.varmintal.com. His barrel tuner


http://www.bostromgunsmithing.com/ImprovedRifleAccuracy.pdf

 

[BountyHunter]

AK muzzle brake offset notwithstanding, the video's relevancy is in the observable orbital movement of the muzzle. That movement is independent of the the AK's muzzle rise that affects it in full auto operation. Admittedly it is not the best video example but it's the best I could find - the pictorial representation of barrel whip is intended to provide the static imagery to support the argument. With or without Google, it ain't a perfect world.

You are missing the key point. The AK74 will have an orbital flex simply due to the opening of the muzzle brake ( 3 o'clock not 12) pushing the barrel down AND left while the standard recoil flex is up. The barrel is going to flex all over due to the two different recoil forces causing flex in different diections.

Now you can take a tuner on a barrel and induce or take out both vertical or horizontal. However not at the same time.

If you are going to say Bill Calfee is wrong a myriad of different Google diagrams with no documentation and a video that is not an accurate depiction is not going to cut it.

 

[rcoody]

You are missing the key point. The AK74 will have an orbital flex simply due to the opening of the muzzle brake ( 3 o'clock not 12) pushing the barrel down AND left while the standard recoil flex is up. The barrel is going to flex all over due to the two different recoil forces causing flex in different diections.

Now you can take a tuner on a barrel and induce or take out both vertical or horizontal. However not at the same time.

If you are going to say Bill Calfee is wrong a myriad of different Google diagrams with no documentation and a video that is not an accurate depiction is not going to cut it.

Calfee knows how to Stop the barrel. Don't care about the physics. It works!

 

[Mikecr]

I believe there are third and fourth tensions -> twist/untwist, and noise(Vaughn's bad vibrations).
And I assign the same value to horizontal as vertical.