7mm STW twist and bullet ??

Discussion in 'Reloading' started by rdm, Aug 24, 2009.

  1. rdm

    rdm Well-Known Member

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    Jan 25, 2003
    I have a 7mm STW with a 1 in 10" twist. The barrel is a Kreiger 30" HV contour, 4 groove. Will the 180gr Berger VLD stabilize with this? Originally just wanted to shoot the 162gr A-Max but I am wondering about the heavier Berger now.
     
  2. kiwi3006

    kiwi3006 Well-Known Member

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    Aug 1, 2007
    Berger state 1 in 9 for the 180. But depending on how fast you are pushing it and at what altitude you might get away with it. The 168 berger will stabilise in a 1 in 10 though.

    I used the 162 a-max in my 7mm mag and it was awesome, unfortunately they are unobtainable in New Zealand at the moment.

    Stu.
     

  3. dirtball

    dirtball Well-Known Member

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    Jan 18, 2007
    Did a quick calculation

    7X57 2450 fps with 9 twist = 196,000 rpm
    7MM Rem Mag 3000 fps 9 twist = 240,000 rpm
    7mm STW 3100 fps 10 twist = 223,000 rpm

    Not sure what velocity Berger bases their twist recomendations on, but I would guess it is something less than the velocity you will get from your 7MM STW.

    Should be OK , worth a try.

    Dave
     
  4. rdm

    rdm Well-Known Member

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    Jan 25, 2003
    Thanks guys.

    Thanks dirtball for running the numbers.

    I'm hoping for 3000-3100fps range for 175-180 grainers, if stability holds up. I was going for 3150-3300fps for the A-Max. I believe those to be resonable numbers for the rifle. Wanting accuracy from this rifle not just velocity. I don't mind trading some velocity for accuracy, if it is there. I get way more jacked up about hitting the target than a 168gr 7mm bullet going 3400fps.