Faster than required twist

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Canadian Bushman, Jul 10, 2014.

  1. Canadian Bushman

    Canadian Bushman Well-Known Member

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    Ive been doing some reading and learning that sometimes running a faster twist than necessary can yeild some positive results. Ive always been cautious of over spinning bullets because of my understanding of precession and lateral jump, and im beginning to question my understanding of these topics and the ideal twist for a bullet.

    Im sure someone here has beat me to this one and was hoping they could share some wisdom with me on stability and how to take full advantage of it.
     
  2. elkaholic

    elkaholic Well-Known Member

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    Bryan Litz (Berger) has recently written about this and I believe it is the best info currently available........Rich
     

  3. Canadian Bushman

    Canadian Bushman Well-Known Member

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    He wrote a new book?
     
  4. elkaholic

    elkaholic Well-Known Member

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    I think there is something posted on the thread concerning the Nosler LRAB thread. He posted some results and I think the publication is forthcoming......Rich

    Basically, you need a 1.5 stability I think? In a nutshell, we are losing some b.c. capability, in some bullets, by not twisting fast enough.
     
  5. Canadian Bushman

    Canadian Bushman Well-Known Member

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    Thanks rich,
    I found the link you were talking about.

    Litz has the book for sale on his website : https://store.appliedballisticsllc.com/mobile/Section.aspx?code=featured

    See ive heard that a stable bullet produces less frontal area and a higher B.C., but this last article was talking about better short range accuracy with long vld bullets, as well as better accuracy past the trans-sonic region, and better terminal ballistics as well.

    They theorized that increasing the twist rate would overcome some imperfections in the bullet that caused the inaccuracy to begin with. I think they were shooting 30 cals with 1:9 twist or 1:8 maybe.

    Its sounds feasible to me.
     
  6. trebark

    trebark Well-Known Member

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    Although my experience is that a bullet that has been 'over twisted' does not yield good accuracy results, I must be in the minority as there are so many people running 1:7 twist AR barrels and shooting 55grain bullets.
     
  7. Canadian Bushman

    Canadian Bushman Well-Known Member

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    Thats the understanding ive been under, and ive believed running the slowest twist possible would let me get all the speed out of a load that i could.

    Im about to re barrel a SA remington and i think ill run a tighter twist than is necessary and see how it plays out.
     
  8. HARPERC

    HARPERC Well-Known Member

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    I "think" we may have to distinguish between cartridges that produce mild, moderate, and extreme velocity.

    I have good luck running all bullets in my Tikka .223 with the 1-8" twist, and my .375
    1-10". The 1-12" .358 Ackley Improved shot well at .35 Whelen velocities, but the wheels seemed to come off at full throttle.
     
  9. Canadian Bushman

    Canadian Bushman Well-Known Member

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    How can we know how much is too much before hand?
    Anything tha produces a stability factor higher than 2.0?
     
  10. HARPERC

    HARPERC Well-Known Member

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    I don't know if we can. It's probably more than just twist, rifling type probably plays a role. I've heard some folks trying the gain twist to reduce stress on the bullet initially.

    The extreme .224's like the TTH, and Clark have drawn some criticism, Kirby Allen I think has a thread here somewhere regarding his efforts with intense .224's.

    Bullet construction has to be a factor, but I suspect it will be seen more often with bigger cases, longer bullets, or trying to run bullets designed for lower velocities.

    Trial and error may be the only way.
     
  11. Canadian Bushman

    Canadian Bushman Well-Known Member

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    I am familiar with the fact that high velocity bullets with tight twist have the potential for destroying bullets. I will look around for info on the rounds you mention in hope of learning more.

    The next rifle i put together will be a 6br, so im not thinking bullet disintegration will not be an issue, but it may not be an extreme enough situation to yeild any discernable results regarding twist either.