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Thread: Barrel vibrations verses barrel stiffness

  1. #1

    Barrel vibrations verses barrel stiffness

    Barrel vibrations verses barrel stiffness


    CYA friends:


    On another thread here on CYA I discussed me accidentally shooting my new MD-PAS triple pistol with a paper wedge between the fore end of the stock and the barrel....


    My muzzle was no longer stopped.


    Because with the wedge in place, my .800" diameter barrel's vibration pattern was reacting to the much stiffer 17" portion of the barrel.


    That wedge became the new face of the action, as far as barrel vibrations were concerned.





    ______________________



    It's fascination how the World turns.



    If any of you have ever owned a Remington Model 700 rifle, and have taken it apart, you'll see that Remington left a bearing pad in the fore end of the stock, to put upward pressure on the barrel.


    Remington had no idea as to why this upward pressure on the barrel caused the entire line of their rifles to shoot better, they just knew they did with that upward pressure on the barrel, especially their light weight sporter sized barrels.



    The reason Remington's barrels, as a whole, shot better with the upward pressure, was because the fore end pad shortened the effective vibration producing stiffness of those barrels.


    The stiffer the barrel, the closer the exact center of the parallel node is to the exit of the crown.


    The closer the exact center of the parallel node is to the crown, the less severe are the muzzle oscillations, hence better accuracy.


    The same thing happened when Remington and Winchester put fore end pressure points in the stocks of their rimfire target rifles.


    ______________________



    Understanding the parallel node, means understanding what a muzzle device is used for, and how it works to enhance accuracy.


    Your friend, Bill Calfee


    _______________________


    PS:



    Back in my varmint hunting days, the first thing I'd do to a new Remington Model 700 rifle was to float the barrel...


    And I wasn't the only one who did this......


    And what I discovered, when I floated those Remington barrels, was some of them seemed to shoot better, but a bunch of them didn't, being perfectly honest with myself.


    But back then, I had absolutely no idea as to exactly why a lot of those Remington's shot better with that fore end pressure.


    Now I do.
    Last edited by Bill Calfee; 1 Week Ago at 01:31 PM.

  2. #2
    Does this mean, that, with an infinite barrel thickness, no MD needed, and reducing the thickness the MD has be heavier and heavier.
    It seems than a proportional increase.
    Have you ever tried to established a mathematical model for an MD?

  3. #3

    Friend PedroS

    Quote Originally Posted by PedroS View Post
    Does this mean, that, with an infinite barrel thickness, no MD needed, and reducing the thickness the MD has be heavier and heavier.
    It seems than a proportional increase.
    Have you ever tried to established a mathematical model for an MD?
    ___________________


    Friend PedroS:


    It's impossible to move the exact center of the parallel node to the exit of the crown, of a gun barrel, without a MD which places the proper amount of weight at the proper location ahead of the crown.


    The above applies to any gun barrel of any stiffness.




    To answer your last sentence:


    In my book, "The ART of Rimifre Accuracy", I have a mathematical formula for establishing MD weight.


    This formula requires the user to establish the exact center of the parallel node of the barrel they're applying it to.


    The problem with this formula, or any formula attempting to establish MD weight mathematically, is that it's difficult to establish the exact center of the parallel node.


    I can get in the ballpark by ringing a barrel.


    But only in the ballpark.



    So we're still left with having to have some minimal adjustability in the MD.



    To further clarify:


    Is there a formula that would allow one to take the exact measurements of a finished gun barrel, and be able to find the exact center of the parallel node?


    I'll answer this way:


    If every gun barrel was made of the exact same material, with the exact same Rockwell hardness value, with the exact same distribution of material around the bore, so the vibration characteristics would be exactly identical, barrel for barrel, then one might be able to determine the exact location of the exact center of the parallel node with a formula based on barrel measurements.



    Your friend, BC



    ___________________


    PS:



    Friend PedroS, may I suggest you run the simple spearment with the 3/32" rod.


    It will answer most every question anyone seriously seeking to understand how a gun barrel vibrates would want answers to.


    I want to add something else here:



    I can take a classic 9x24 barrel, that I've just fit to a Class A contraption, and set the standard HH/MD before I run my first range test, and about half the time it will never be moved again.....so can the other CYankee schmidts like Tom Wilkinson, the Ole Hawk and Jeff Patterson.


    But, I can't do it 100% of the time, nor can they.


    So there's probably no 100% perfect formula that can be contrived for determining these things.







    Last edited by Bill Calfee; 1 Week Ago at 06:32 PM.

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