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Thread: Barrel Twist in relation to Bullet Yaw

  1. #21
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    Quote Originally Posted by Ernst View Post
    Exactly, I mean, even a pre-schooler knows this stuff, right?
    09-14-09, 20:12...

  2. #22
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    Quote Originally Posted by Molon View Post
    As long as the bullet is adequately stabilized at the muzzle, barrel twist rate has no effect on the terminal ballistic properties of 5.56mm ammunition.
    I apologize for resurrecting this thread, but I'm researching a retro A1 build and I wanted to understand a bit more about the 1:12 twist rate (vs. the "modern" 1:7 twist rate).

    From the information shared here, it seems that the following statement is wrong?

    "This is important if you're shooting living targets, e.g., hunting because the fragments, combined with hydrostatic shock, tend to produce a much larger and more potentially lethal wound cavity than a bullet that stays in one piece. The relevance to rifling twist is that usually only a very rapidly spinning bullet - say, over 250,000 rpm - will fragment like that. A 1:12 twist won't produce that effect"
    https://www.at3tactical.com/blogs/ne...rifling-part-2
    So, 55gr XM193 out of a 14.5" barrel with 1:12 twist rifling goes around ~3000 fps and is spinning at 180,000 rpm according to this RPM calculator:
    http://www.accurateshooter.com/techn...tes-stability/

    Same bullet weight, same barrel length, but 1:7 twist rifling and slightly less velocity (~2900 fps) produces ~300,000 rpm.

    The difference in RPM only effects the flight path of the bullet, and not the lethality -- right?
    "The nation that will insist on drawing a broad line of demarcation between the fighting man and the thinking man is liable to find its fighting done by fools and its thinking done by cowards."
    William Francis Butler

  3. #23
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    Quote Originally Posted by Molon View Post
    As long as the bullet is adequately stabilized at the muzzle, barrel twist rate has no effect on the terminal ballistic properties of 5.56mm ammunition.
    I believe this statement sums up the affect twist rate has on terminal ballistics.
    Train 2 Win

  4. #24
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    For practical understanding that statement still holds true. The simple answer is "barrier blind expanding" and then go train.

    I have seen some discussions about higher RPM causing slightly more damage with some bullet designs, I believe fragmenting.

  5. #25
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    Quote Originally Posted by Todd.K View Post
    For practical understanding that statement still holds true. The simple answer is "barrier blind expanding" and then go train.

    I have seen some discussions about higher RPM causing slightly more damage with some bullet designs, I believe fragmenting.
    Another reason to go 1/7 albeit a small one.

    Quote Originally Posted by DocGKR View Post
    There is ongoing new research indicating that with some expanding projectiles, especially in shorter barrels, FASTER twists produce improved terminal ballistic performance...

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