Ballistics
The science of projectile flight, how a bullet behaves from the moment the primer fires until it hits the target.
Three slices of the same field. Internal ballistics covers what happens inside the barrel: pressure curves, propellant burn, bullet engraving into the rifling. External ballistics covers what happens in flight: gravity, air drag, wind, spin drift. Terminal ballistics covers what happens on target: penetration, expansion, energy transfer.
Long-range shooters spend most of their time on external ballistics. That’s where the math determines whether you hit.