Ballistics is the science of the propulsion, flight, and impact of projectiles. As it regards guns, it is usually divided into three parts; they are:

1. interior ballistics — the science of the propulsion of a projectile and its movement inside a gun;
2. exterior ballistics — the science of the movement of a projectile while in flight; and
3. terminal ballistics — the science of the movement of a projectile at, or in, the impact point.

related:

• ballistics, exterior
• ballistics, interior
• ballistics, terminal

Footnotes / Sources:

“Glossary ⇒.” Sporting Arms and Ammunition Manufacturers’ Institute. Ed. SAAMI’s Technical Committee. Web. 15-18 Jan. 2011.