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Thread: 308 Ballistic Coefficient
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25-10-2013, 10:00 #1
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308 Ballistic Coefficient
HI
Does any body know the ballistic coefficient of the FMJ 143grain 308 point .
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25-10-2013, 10:31 #2
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Re: 308 Ballistic Coefficient
Chuckhawks:
The Sierra 150 grain boat tail spitzer has a ballistic coefficient (BC) of .416 and a sectional density (SD) of .226.
Hope it helps!
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26-10-2013, 16:06 #3
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Re: 308 Ballistic Coefficient
According to PMP the BC is .456, this is from the March 1998 Magnum.
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26-10-2013, 17:43 #4
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Re: 308 Ballistic Coefficient
I see that Quick Load also lists the G1 as 0,456 for this bullet.
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28-10-2013, 16:30 #5
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Re: 308 Ballistic Coefficient
Depending on what type of program you are using, you have to make some adjustments to the quoted BC figure, to get more accurate predictions. If your program uses a single "G1" BC figure, use 0.40. (G1 is not really all that relevant to Spitzer-BT bullets, and the BC figure decreases as bullet velocity goes down.)
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31-10-2013, 16:34 #6
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Re: 308 Ballistic Coefficient
no ways will it have a .456 bc that's better than a lot of 155gr match bullets.Got some will test them
myself to check bc values.
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31-10-2013, 16:40 #7
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01-11-2013, 12:25 #8
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Re: 308 Ballistic Coefficient
No short answer there. A good read, to explain all the intricacies, in easy understandable language is: "Applied ballistics for long-range shooters" by Bryan Litz.
In short: The commonly quoted G1-referenced BC figure, is not constant for most Spitzer-BT bullets. It starts high, and decreases as velocity deminishes. So .456 might be possible at about 4000 fps, but not at 2500 fps, assuming std atmospheric conditions, at sea level.
With most trajectory predictions, you still have to test physically. Adjust the figures you feed your computer, untill the trajectory predictions match with your actual range results. That's the fun part...
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30-07-2019, 07:56 #9
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