What does the term "impact velocity" refer to in terminal ballistics?

The term "impact velocity" specifically refers to the velocity of a projectile at the moment it strikes a target. This measurement is crucial in terminal ballistics because it influences how the projectile behaves upon impact, including penetration, expansion, and the overall effectiveness of the projectile in delivering energy to the target.

Understanding impact velocity helps in diagnosing the performance of different projectiles and their effects based on their speed at the moment they reach the target. This concept is vital when considering factors such as tissue damage in ballistic studies or the effectiveness of projectiles in various scenarios.

The other options focus on different phases of the projectile's journey, such as initial speeds or averages during flight, but do not specifically address the conditions at the point of impact, which is the essence of impact velocity.