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Speer ballistic coefficients believable?

Discussion in 'Handloading and Reloading' started by GooseGestapo, Oct 21, 2017.

  1. GooseGestapo

    GooseGestapo Member

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    I was looking at various .257" bullets on MidwayUSA's web site.

    They show the b.c. For the 120gr Speer at .480. This is somewhat higher than the Berger 115gr VLD (.465), or Sierra 117gr GK (.410) or 117gr Hornady btspt (.391) or 117gr SST at .465.

    Anybody shot them at distance to verify this seeming exageration?
     
  2. Laphroaig

    Laphroaig Member

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  3. Berger.Fan222

    Berger.Fan222 Member

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    I'd go with the Speer number (0.405).
     
  4. GooseGestapo

    GooseGestapo Member

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    .405 is more believable. Thanks!
     
  5. VoodooMountain

    VoodooMountain Member

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    405 makes more sense but several people have called out speer on this very issue. Their btsp line seems to have optimistic bc listed sometimes.
     
  6. higgite

    higgite Member

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  7. hdwhit
    • Contributing Member

    hdwhit Member

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    The "Ballistic Coefficient" is not a static number that applies to a projectile at all times, conditions, and points in the flight envelope. Unless you know the velocity and conditions under which a particular projectile B.C. was measured and you know the B.C. of the projectile you are proposing to compare it with, B.C.s reported by one manufacturer may have limited comparability with B.C.s reported by another.
     
  8. Sunray

    Sunray Member

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    Ballistic coefficients are about the bullet's ability to move through the air. Has nothing to do with distance. Has to do with the weight and shape of the bullet. The BC doesn't really mean much anyway. You load according to the bullet weight, not how it moves through the air.
     
  9. someguy2800

    someguy2800 Member

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    That seams a little optimistic to me. They list there 120 grain fusion bullet at .468 which I also have a hard time believing but they are an excellent bullet nonetheless.
     
  10. jmr40

    jmr40 Member

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    BC doesn't have anything to do with how you load, but that wasn't the question. And BC can be huge. A 180 gr bullet with a very high BC fired from a 30-06 will impact with more speed and energy at 100 yards than a 180 gr bullet with a very poor BC fired from a 300 WM. The same high BC bullet fired from a 308 will beat a poor BC bullet fired from a 300 WM at 200 yards. That means something.

    BC does change as velocity changes. Some bullet manufacturers state BC at a specific speed, others at an average speed over a set distance. Some are more accurate than others. Berger tends to be pretty accurate with the numbers they state.
     

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