swift bullet?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Stick, Jan 4, 2013.

  1. Stick

    Stick Member

    Messages:
    14
    Joined:
    Mar 7, 2011
    Just trying to figure out why the scirocco 2 is so high in bc. The 6.5 130 grn accubond is .488 and the swift 130 is .571. Why is this? any ideas? Thanks Rob.
     
  2. elkaholic

    elkaholic Well-Known Member

    Messages:
    5,355
    Joined:
    Dec 4, 2008
    Not absolutely sure on this but I think the Swift is a secant ogive and the AB is a tangent which gives the Swift a more streamlined nose.....Rich
     

  3. Edd

    Edd Well-Known Member

    Messages:
    2,395
    Joined:
    Jan 26, 2011
    From another thread.............

    I measured a G1 BC of .491 for that bullet. G7 BC is .251.

    It's got a decent ogive design, but a poor (short and steep) boat tail for base drag reduction. Certainly not a design that could possibly produce a .571 average G1 BC. Even at 3000 fps, the G1 BC is just .515, degrading to .453 at 1500 fps.

    A thick jacket for a long bullet...? Sure it makes the bullet longer, but that doesn't mean high BC. Lengthening the nose and tail will reduce drag, but lengthening the bearing surface does nothing for drag so it's irrelevant.

    None of my analysis included group shooting (precision) testing so I can't comment on that. They may be extremely precise, but the BC claim is not accurate.

    -Bryan
    __________________
    Bryan Litz
    Ballistician
     
  4. elkaholic

    elkaholic Well-Known Member

    Messages:
    5,355
    Joined:
    Dec 4, 2008
    Are "decent" and "secant" synonymous? :D Just kidding!......Rich
     
  5. CRaTxn

    CRaTxn Well-Known Member

    Messages:
    150
    Joined:
    Jan 18, 2009
    Stick,
    I have the wonderful BS Buster investment book APPLIED BALLISTICS FOR LONG-RANGE SHOOTING, it is a cheap way to cut thru the crap.[Much cheaper to read about Bryan's work than have to load, shoot and decipher the data myself] Ref. page 420 on this 130 gr Scirocco. I bought some from Swift in their booth at the DSC Convention a few years back, kind of like a buxom blonde butt with a flat arse.
    I am hoping Bryan will offer online updates to his book.