4.0 The Ballistic Coefficient
In the previous section the ballistic coefficient was introduced in its historical context, that is, as a parameter which was discovered and used to simplify the calculation of bullet trajectories. Today, shooters recognize the ballistic coefficient as a measure of the ballistic efficiency of a bullet. What this means precisely is that if we compare several bullets all fired at the same muzzle velocity, then the higher the ballistic coefficient of any bullet, the flatter it shoots, the better it bucks the wind, and the better it retains its velocity as it travels downrange.
This section is devoted to more detailed discussions of this very important bullet characteristic.Section 4.1 describes what the ballistic coefficient is, relating it to the sectional density and the shape factor of the bullet. Section 4.2 describes important effects of the ballistic coefficient on bullet trajectories. It attempts to provide the reader with an overview of the importance of this parameter to trajectory flatness, remaining velocity, and accuracy.
Section 4.3 describes how we measure ballistic coefficients by firing tests in Sierra’s underground range. Section 4.4 summarizes important lessons about ballistic coefficients which we have learned in 25 years of test experience. Finally, Section 4.5 describes ballistic coefficient test results for three handgun bullets in the transonic velocity range (900 to 1200 fps), showing that radical changes in ballistic coefficient can occur in this velocity range.