What defines external ballistics?

External ballistics refers specifically to the study of a projectile's behavior in flight after it has been propelled from a firearm and before it makes contact with a target. This encompasses various factors such as trajectory, velocity, air resistance, and the influence of environmental conditions like wind and humidity during the projectile's flight path. Understanding these dynamics is critical for accurate long-range shooting, as it helps predict where a projectile will land based on its initial conditions.

The other options focus on different aspects of ballistics. The behavior of a projectile after it hits the target relates to terminal ballistics, which studies the effects of the projectile upon impact. The events within the firearm pertain to internal ballistics, which examines the processes occurring from the moment of ignition until the projectile exits the barrel. Lastly, considerations regarding the projectile's impact effects also fall under the realm of terminal ballistics. Thus, option C is the correct choice as it precisely defines the scope of external ballistics.