BC calculations with corresponding velocity

SDHNTR

WKR
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Aug 30, 2012
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Formulaically, how is BC calculated? I've never given much thought to BC beyond getting my muzzle velocity and then truing BC for drops at longer ranges. I did have a recent situation where the BC was off from what the manufacturer published, which I know is common, but it got me thinking. If I had to reduce my BC for accurate drops, does that mean my velocity was slower or faster than the test rifle the factory used? For example, I was shooting a .260 rem, when that same bullet could've been fired from a 6.5prc or something with much faster velocity. So how would that change my real BC? Or stated differently and more generally, does greater velocity equate to a higher BC or vice versa?

Which then got me further thinking that it sure would be helpful if manufacturers would also publish the rifle and the MV of the test rifle they used to get their BC #'s, so we could then adjust up or down versus our own rifle's velocity. Or is it not that simple?
 
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Team4LongGun

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Way too many variables, even if they did publish all of that, one would still need to true.

While more info wouldn't hurt, so many folks get wrapped around the axle (not saying you are) over published BC's. I take them as a starting point and true based on actuals. Most longer range shooters spend a ton of money and time on components, yet some want to complain a large manufacturer's BC value isn't matching their own-seems like the most important part to get right and verify with your specific rifle, load, environmentals etc. It's part of the fun for me.
 
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SDHNTR

WKR
Joined
Aug 30, 2012
Messages
7,265
Way too many variables, even if they did publish all of that, one would still need to true.

While more info wouldn't hurt, so many folks get wrapped around the axle (not saying you are) over published BC's. I take them as a starting point and true based on actuals. Most longer range shooters spend a ton of money and time on components, yet some want to complain a large manufacturer's BC value isn't matching their own-seems like the most important part to get right and verify with your specific rifle, load, environmentals etc. It's part of the fun for me.
Valid point. I still true up and once solved have never given it much additional thought. Guess I just generally wanted to take some of the witchcraft out of the process and to learn if (all else assumed equal) the same bullet going faster or slower increases or decreases BC.
 
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