Explosive

Explosives are a type of ammunition.

Fallout, Fallout 2
In Fallout and Fallout 2, the only types of explosive ammunition are the explosive rocket and the rocket AP.

Fallout 3
Explosives are almost always more powerful the closer a target is to the center of its blast radius $$ This blast radius is known as the Area of Effect, or AoE.

Examples of explosive ammunition are the Missiles that are used by the Missile Launcher and derivatives, and the Mini Nuke shell for the Fat Man catapult.

Fallout: New Vegas
Fallout: New Vegas has significant numbers of explosive ammo, such as:
 * 25mm Grenade
 * 25mm Grenade, High Explosive
 * 40mm Grenade
 * 40mm Grenade, Incendiary
 * Mini Nuke
 * Missile
 * Missile, High Explosive
 * Missile, High Velocity

Fallout 4
Explosive weapons in Fallout 4 include:

Fallout Tactics
Fallout Tactics has several more kinds of explosive ammo types, including explosive rockets, rocket APs, rocket sabots, and 40mm grenades.

Fallout: Brotherhood of Steel
The only explosive ammunition in this game is the Rocket Ammo, which can be fired by a Home-Made Rocket Launcher or the improved version, the Rocket Launcher.