90 gr. Swift Scirocco

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Greg Duerr, Aug 21, 2012.

  1. Greg Duerr

    Greg Duerr Well-Known Member

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    Ive heard that its hard to get the 90gr. Scirocco to shoot out of a standard 1x10 twist in the .243....................What about the 1x9?

    For those who shoot the 90gr. Scirocco what works for you..................and how does the bullet perform.?

    G
     
  2. squeezenhope

    squeezenhope Well-Known Member

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    Going the wrong direction. IF the 90 grain will not stabilize at 1in10 it would be highly unlikely for it to improve by going to a faster twist.
     

  3. Greg Duerr

    Greg Duerr Well-Known Member

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    So I should go to a 1x12 or 1x14?????? I think your heading in the wrong direction
     
  4. squeezenhope

    squeezenhope Well-Known Member

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    That is exactly what I am saying, but I think 1x12 would be plenty slow for a 90 grain 6mm bullet. If you think I am going the wrong way you might want to research the evolution of twist used by Remington for the .244/6mm.
     
  5. Greg Duerr

    Greg Duerr Well-Known Member

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    I heard that the standard .243 twist is 1x91/2, I think Berger sugjests a 1x9 for their 95gr and a 1x8 for their 105 the long Scirocco would need a faster twist than the 1x10 if it wont shoot in the 1x10 my rifle has a 1x9 twist and was told by Swift that the 90gr. Scirocco shoots best in a faster twist rate.........most guys I have talked to could not get them to shoot well in their standard factory barrels....................
     
  6. TJAY

    TJAY Well-Known Member

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    Rule of thumb.

    Longer bullet needs faster twist rate.

    Lighter bullet=shorter bullet, heavy bullet=longer bullet

    90 gr Swift Scirocco is a long bullet for its calibre
     
  7. squeezenhope

    squeezenhope Well-Known Member

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    AGREED. But this post started out asking about 90 grain bullets, but somehow has morphed to 105's??? Moving on.
     
  8. Beng

    Beng Well-Known Member

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    This website says the bullet is 1.132" in length.
    Using the jbm stability calculator, I get a minimum twist rate of 8.5" per revolution at sea level for 3000f/s mv.
    The Applied Ballistics point mass solver agrees.
     
  9. angus-5024

    angus-5024 Well-Known Member

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    "Going the wrong direction. IF the 90 grain will not stabilize at 1in10 it would be highly unlikely for it to improve by going to a faster twist."

    heavier, longer bullets using a slower twist ehh? (im Canadian, excuse the ehh).
    Well, i think that you should chamber a .243 with a 1-12 or 1-14 tube and let us know how it works for you with the 90 grainers.:D

    berger recomends a 1-9 twist minimum for their 95's. got a box of em in my hands. A 1-10 may stabilize the 90's, but it'll hit or miss. A 1-9 will do the trick though.