264 twist rate and bullet choices

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by fisherman983, Nov 22, 2012.

  1. fisherman983

    fisherman983 Well-Known Member

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    after doing some inconclusive load developement with a 264 win mag, i noticed that berger recoments a 1:8 twist rate for their 140gr pill, while my rifle has a 1:9 twist. have i been wasting my time with a bullet that wont stabilize in my rifle?
     
  2. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

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    Are you testing at 200+meters? Did you do a seating depth test after your ladder test? I would think the 130g would be better suited to you twist rate.
     

  3. fisherman983

    fisherman983 Well-Known Member

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    testing at 100 yds, did not do a seating depth or ladder test
     
  4. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

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    OK well 100m is not enough to tell if the bullet has settled down. If you have not done either of them then yes your wasting bullets, regardless of whether or not the bullet will stabilize.
     
  5. Mikecr

    Mikecr Well-Known Member

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    You're probably fine in 9tw Fisherman.
    Berger recommends an optimum twist under ICAO conditions(same conditions of BC rating). Seal level, 59deg, 0%Rh.
    8tw puts the 140VLD Sg at or above 1.5 here, and this provides margin for all things affecting stability.

    9tw puts Sg about ~1.3 at ICAO and there is no evidence yet that this would degrade accuracy for you. It might if your muzzle pressures are in excess(short barrel), or your crown is less than perfect.
    What conditions will you be shooting in(elevation, temps)?

    I've used 140VLDs in 8.5tw here at sea level, and around 50degs with fine performance.
    My Sg is typically running ~1.4
    I personally would not worry about 9tw unless I was challenging stability in another regard.
     
  6. fisherman983

    fisherman983 Well-Known Member

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    shooting conditions will be typical oregon coastal weather, temps in the 40's and 50's with lots of rain and elevatoin from 0-1500 ft with occaisional trips to other states such as wyoming and hopefully trips to montana and idaho and anywhere else i may be luck enough to draw a tag as well with shooting conditions unknow at those locations
     
  7. .284

    .284 Well-Known Member

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    I never had a problem in my 264 win mag sendero which is a 9 twist. I also shoot the 140 bergers in a 6.5-06 8.5 twist. They are much more accurate in that rifle but I assume that is because it is a custom.
     
  8. Cold Trigger Finger

    Cold Trigger Finger Well-Known Member

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    Sounds kinda complicated.
     
  9. Bob L.

    Bob L. Well-Known Member

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    I just had a 264 win mag built with a 27" Lilja 9 twist. Lilja said it would stabilize 140's just fine.
     
  10. benchracer

    benchracer Well-Known Member

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    I know that some have reportedly had problems stabilizing 140g Bergers with a 9 twist, but it hasn't happened to me.

    My 6.5x55 with a 9 twist Shilen stabilized the 140 Bergers with no issues and shoots them very accurately. Even at the starting load, going pretty slow, it was shooting ragged hole three shot groups with no signs of bullet instability.

    Of course, rifles and barrels are individuals, but if my Swede can go slow and stabilize a 140 Berger, odds favor your .264WM being able to do it IMO.

    FWIW, I have a 9 twist .264WM, too. I plan to shoot 140g AMAX's in it, but haven't gotten that far with load development. So far, the seating depth tests have shown it to really like 140g Nosler Partitions. That will take care of the close stuff. If it shoots the AMAX's anywhere near as well as the partitions, I will be very happy.
     
  11. Edd

    Edd Well-Known Member

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    I just ordered a 6.5 barrel anticipating using 130gr Cutting Edge bullets. They told me a 7.5 twist would be perfect for that bullet. It is almost exactly the same length, .005" shorter, as the 140gr Berger.
     
  12. Mikecr

    Mikecr Well-Known Member

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    Edd, this is because lowering sectional density(with all else equal) reduces both BC and stability.
    This is a special case in that normally lighter bullets are not the same dimensions as heavier bullets.
     
  13. rooster721

    rooster721 Well-Known Member

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    The way I understand, and so far HAVE seen myself as well, a higher velocity will definitely help in stabilizing a heavier than recommended bullet (like in this 264 140gr case) 264wm is a pretty quick load in regards to average calibers.. it's extra speed helps make the 140gr bullets "work" through a 1:9 vs the recommended 1:8 twists.

    BC and twist rate (so I was told & understood anyways) are based on a 3000fps velocity... no more. Velocities significantly increasing from 3000 will gradually increase BC and aid in stabilizing heavier bullets.

    **Guys loading faster than that are most likely the guys that are having success with them, Guys loaded at 3000 or any-much below (possibly with rifles having shorter-barrels) are most likely the guys having trouble with them
     
  14. Mikecr

    Mikecr Well-Known Member

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    Rooster the truth in that is that higher velocities can help, a little.
    Very little