Long Range and BC – What Difference Does It Make ?

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There are a lot of misconceptions about what the Ballistics Coefficient can and cannot do for you…. Here is the summary….

1. It makes little difference in trajectory, until you really start stretching out in range.
2. It makes a huge difference in wind drift. Twice the BC, half the wind drift.
3. It makes a huge difference in retained velocity and energy.

For the shot criteria I used a 75 gr. bullet at 980 fps, which is 160 FPE of muzzle energy, and the rifle is sighted at 100 yards…. I then plotted Drop, Drift, Velocity and Energy vs. the BC, for four values of BC…. 0.05 (a typical pellet)…. 0.10 (a large cal, low SD bullet)…. 0.20 (a smaller cal, mid SD bullet)…. and 0.40 (a small cal, high SD bullet, used for comparison purposes only)…. Note that each BC is twice the previous one…. Here is what happens as you increase the BC….

Note that the biggest difference in drop is between pellets and bullets, and even that is not really significant until you push over 200 yards….

Wind drift is inversely proportional to the BC…. If you double the BC, you basically cut the wind drift in half….

The higher the BC, the less velocity is lost as the bullet goes downrange…. Once again, the difference between pellets and bullets is huge…. and BC becomes more important as range increases….

Split into two posts because I had too many graphs….

Bob

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[rsterneParticipant]

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Continued from above…. this graph is for the Retained Energy….

This is probably where BC makes the biggest difference…. Consider these comparisons, starting with a muzzle energy of 160 FPE (a 75 gr. bullet at 980 fps)….

If the BC is 0.40, the retained energy is 119 FPE at 400 yards….
If the BC is 0.30, the retained energy is 119 FPE at 300 yards….
If the BC is 0.20, the retained energy is 119 FPE at 200 yards….
If the BC is 0.10, the retained energy is 119 FPE at 100 yards….
If the BC is 0.05, the retained energy is 119 FPE at 50 yards….

There can be no doubt that bullets are far superior to pellets for reduced wind drift, retained velocity and retained energy, because they have roughly twice the BC…. If you double the BC again, because of careful selection of caliber and bullet design…. you can reap those gains again….

Bob

[Author]

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