.308 twist rates

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Gerald89, Feb 28, 2006.

  1. Gerald89

    Gerald89 Well-Known Member

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    Hello,

    Please could someone tell me the twist rates needed across the .308 range of bullets?


    One twist rate for bullet weight range between 165Gr and 240Gr would be nice?

    Thanks
    Jeza
     
  2. Bart B

    Bart B Well-Known Member

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    Twist needs to be matched with muzzle velocity. What cartridge will you be shooting these out of? And that's quite a bullet weight spread you want to use.

    For example, with a .308 Win. using a 165-gr. bullet, a 1:12 is hard to beat. But with a 240-gr. bullet, it'll take a 1:8 twist to shoot that long, heavy bullet accurate from a 28 inch barrel. A shorter barrel used for the 240 may well need a 1:7 twist.

    I talked with David Tubb some years ago about his .308 Win. shooting 250-gr. Sierra HPMK's. He said he tried a 1:9 twist shooting them out at 2150 fps but they didn't do well at 600 yards. Changing to a 1:8 twist solved the problem.
     

  3. bailey1474

    bailey1474 <strong>SPONSOR</strong>

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    A 10 twist will shoot all of these just fine. If I were ordering today though, I would probably get a 9 twist and not look back.
     
  4. Michael Eichele

    Michael Eichele Well-Known Member

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    MINIMUM 10x for the 240 SMK. 9 would be better.
     
  5. Gerald89

    Gerald89 Well-Known Member

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    Thanks for the info!

    300wsm is going to be my cartridge.

    What happens if you use a lighter bullet and spin it too fast does it just lose accuracy or do damage?

    Thanks again
    Jeza
     
  6. Desert Fox

    Desert Fox Well-Known Member

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    1 in 12 is ideal for all range of bullet weight for the 308, from 150 up to 180. My 308 Tactical Rifle has 25" Pac-Nor Super-Match 3 grove 1 in 12 and love the Sierra MK 168 and 175's.
     
  7. JR

    JR Well-Known Member

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    [ QUOTE ]
    Twist needs to be matched with muzzle velocity. What cartridge will you be shooting these out of? And that's quite a bullet weight spread you want to use.

    For example, with a .308 Win. using a 165-gr. bullet, a 1:12 is hard to beat. But with a 240-gr. bullet, it'll take a 1:8 twist to shoot that long, heavy bullet accurate from a 28 inch barrel. A shorter barrel used for the 240 may well need a 1:7 twist.

    I talked with David Tubb some years ago about his .308 Win. shooting 250-gr. Sierra HPMK's. He said he tried a 1:9 twist shooting them out at 2150 fps but they didn't do well at 600 yards. Changing to a 1:8 twist solved the problem.

    [/ QUOTE ]

    Well, actually twist rate needs to correspond with the length of the bullet, in order to stabilise said bullet...So, if you were to shoot the 240's rather regularly, you would want the twist to match that bullet...Twist for the longest bullet you intend to use, you may need to slow the velocity down for the lighter bullets...Just running numbers in my head, I think a 1/9 would stabilise the 240 in WSM..1/8 definitely would, but might copper foul like a mutha with the lighter faster bullets..

    Just my 2 pence

    JR
     
  8. Brown Dog

    Brown Dog Writers Guild

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    [ QUOTE ]
    300wsm is going to be my cartridge.

    [/ QUOTE ]

    Jeza, I take it your application for 308 went better with plod than you expected?!!
     
  9. Pete Lincoln

    Pete Lincoln Well-Known Member

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    Me, i'd go 1 in 10.
    JR, you ready for some weizen bier mate?
    Matt, check you email,

    Pete
     
  10. Gerald89

    Gerald89 Well-Known Member

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    Thanks everyone,

    Matt, I haven't got to see him yet (one of my referees didn't send back his form until I chased him).

    I am just assuming that I can have one on a target basis even if they say no to deer etc , fingers crossed still!