Continuing on the Ballistics Basics series (Check out episode 72 on Twist Rate if you want to start from the beginning), Pliny describes the differences between internal, external, and terminal ballistics. Every projectile in flight has three major periods of ballistics that can be analyzed, and different features or properties are emphasized based on the desired outcome. Too many hunters and shooters gloss over the science and the "but why", as they learn about shooting.