BC stands for Ballistic Coefficient
Ballistic Coefficient (BC) is a measure of external ballistic performance for bullets. The higher a bullets BC is, the less drop, and wind deflection it will have at all ranges for a given muzzle velocity and environment.
BC is a number that can be used as an input for ballistic solvers to predict trajectories. BC is also used as a selling point for long range bullets so due to this marketing use, sometimes BC’s are inflated or skewed by manufacturers to sell more bullets. As a long range shooter who cares about hitting targets, it’s important to understand the basics of BC so you’re not mislead by marketing hype.
To be more specific, Ballistic Coefficient is a measure of how well a bullet retains velocity as it flies downrange, in comparison to a standard.
BC’s can be referenced to different standards.
The two most common standards in use are:
G1 for old, flat based, blunt nosed bullets
G7 for modern, spitzer nosed, boat tailed bullets
Figure 1.
G1 (left) vs. G7 (right) standard drag models. G7 is much closer to modern long range bullets.
BC’s referenced to the G1 standard are higher numbers, but as you can tell from the image above, not the best representation for modern long range bullets. BC’s referenced to the G7 standard are lower numbers, but are a more accurate representation of a modern bullets drag at all velocities.
The following articles in the “What is a BC?” series will cover many aspects of BC (Ballistic Coefficient) including variation, velocity dependence, marketing influences and many other considerations that long range shooters should be aware of when considering when selecting a bullet for their application.
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