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Thread: Whipping Barrel During Discharge

  1. #11
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    Nov 2016
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    The last stage of accurising is varying the powder charge for a given load until you find a node in the whipping action. The giveaway is a sudden tightening up of your group. If you continue to increase or decrease charge in the same direction, groups will open up again. To achieve this you need repeatability in every other aspect, especially bullet weight.

    Sent from my H3123 using Tapatalk
    Google will explain the node concept if you wish to research this.
    Last edited by GrayTech; 01-21-2019 at 09:19 PM.

  2. #12
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    Feb 2014
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    Quote Originally Posted by epanzella View Post
    The barrel harmonics start as soon as the pressure builds behind the bullet. As with any harmonic wave it has to reverse direction when it reaches maximum defection and it is at this point that the barrel is briefly stationary. Loads tuned to have the bullet clear the rifling during this direction reversal will be the most accurate. The more out of square the parts are to each other (barrel to receiver, receiver to bolt, bolt to barrel) the greater amplitude of the harmonics which will make the gun more "fussy" as far as the loads it will shoot well. Conversely when a gun is "blueprinted", all the mating parts of the rifle are squared as perfectly to each other as humanly possible, reducing the amplitude of harmonics, resulting in a rifle that shoots many loads well. The gun also begins to move from recoil while the bullet is going down the barrel and is another factor that has to be dealt with. This is why gun weight, stock fit, and good shooting form are also important.
    Quote Originally Posted by GrayTech View Post
    The last stage of accurising is varying the powder charge for a given load until you find a node in the whipping action. The giveaway is a sudden tightening up of your group. If you continue to increase or decrease charge in the same direction, groups will open up again. To achieve this you need repeatability in every other aspect, especially bullet weight.

    Sent from my H3123 using Tapatalk
    Google will explain the node concept if you wish to research this.
    Lots of good comments and explanations here, but these two are especially on point. Understanding "whip" as vibration and tuning to work with that vibration are key points to accuracy.

  3. #13
    Join Date
    Sep 2007
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    Wasilla, Alaska
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    Yondering,
    I agree with your comment. There is a lot of good information.

    Thanks to all for weighing in on this thread.

    Harold
    For those having fought for it, Freedom has a flavor the protected will never know.
    Freedom is only one generation away from extinction.

  4. #14
    Join Date
    Aug 2018
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    Tai Tokerau - NZ
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    For anyone devolping loads, do "ladder tests" The method is posted online, but generally take the MAX load, subtract 15% and load up in 0.2 grain increments from that number.
    Shoot them one after at the same Pont of Aim. You'll get vertical dispersion, with tighter groups at/around certain loads. STOP when you start getting over pressure signs on your cases/primers.
    Then pick one of the close groups, pick a load in the middle and work on that- these are your nodes.

    I have to disagree with epanzilla, from my reading, the "donut" pressure wave gong down the barrel will cause the muzzle to expand and if the bullet leaves at this point it loses that last bit of stabilisation and can yaw.

  5. #15
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    Jul 2008
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    Barrel vibration would be a more accurate term than barrel whip. At the macro level everything bends and flexes a measurable amount no matter how small the forces or how strong the material is if the measuring equipment has enough resolution and accuracy to measure those forces. And there's little difference between a rifle barrel and a tuning fork. With a 36 x scope I can see my heart beat slightly moving the cross hairs even when using a rest. There's zero doubt those heart beats are also vibrating the barrel all the way out to the tip. Since the speed of sound is over 13,000 mph in steel you can bet the barrel is starting to vibrate as the sear starts to move in the trigger assembly, and certainly between when the trigger breaks and long before the firing pin even hits the primer. The mechanical vibrations within the rifle are impossible to fully eliminate. So as others have already pointed out finding a bullet weight and shape, seating depth, powder type, burn speed and amount, primer as well as paying attention to absolute reloading consistency allows fine tuning of those vibrations so the muzzle is at the same vibration point as much as possible. There's a whole lot more going on within any gun before the primer ignites than most seem to think. Yes the major vibrations are caused by the primer and powder ignition, gas expansion and the bullet acceleration until it leaves the barrel. But there's still other causes that should be considered as well.

  6. #16
    Join Date
    Sep 2013
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    This video shows a considerable amount of "animation" of the rifle barrel.

    https://www.bing.com/videos/search?q...B1&FORM=VDQVAP

  7. #17
    Join Date
    Oct 2015
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    Wyoming
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    If you search for "barrel tuners," you will find a good deal of data, testing, etc on the issue of barrel tuners, and how much they can improve group sizes on already very precise rifles, both .22LR match rifles (Annies, Walthers and so on) and on centerfire rifles.

    Browning/Winchester developed a line of rifles with tuners on them that also doubled as muzzle brakes - called the "BOSS" system. I have one on a .338 Model 70. I can take groups from over 2" at 100 yards to about 3/4" or less by only adjustment of the BOSS brake.

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