Gametitle-FO3 MZ.png
Gametitle-FO3 MZ.png

The drone cannon Ex-B, is a unique weapon added to Fallout 3 by the Mothership Zeta add-on, and is carried by the experimental weapons drone.


The Ex-B (explosive-bolt) is an alien experiment that involves equipping the guardian drone model of defensive robot with a cannon that fires spheres of energy that explode upon impact. The Ex-B has a very long range, and if aimed manually, can be used as an effective sniper. The Ex-B can be shot effectively underwater without adverse effects. This variation allows the fired projectile to bounce off solid objects once.

The drone cannon, however, is an ineffective V.A.T.S. weapon, as the fired projectiles will arc toward their targets; since the game does not compensate for gravity in V.A.T.S., this can leave projectiles several meters away from their intended targets.


The drone cannon Ex-B can successfully fire about 417 times from full condition before breaking; the same amount as a normal drone cannon.


Drone cannon Mothership Zeta (add-on)


Weapon name (current weapon is highlighted)- Weapon name (melee or unarmed)Attacks in V.A.T.S.- Attacks in V.A.T.S.
Weapon name (current weapon is highlighted)- Weapon name (gun, energy or explosive)Action point cost- Action point cost
Damage per attack (damage per projectile)- Damage per attack (damage per projectile)Damage per action point- Damage per action point
Damage per second- Damage per secondWeapon spread- Weapon spread
Area of effect damage- Area of effect damageMagazine capacity (shots per reload)- Magazine capacity (shots per reload)
Effect damage & duration- Effect damage & durationDurability (number of attacks before breaking)- Durability (number of attacks before breaking)
Bonus effects- Bonus effectsWeight- Weight
Attacks per second- Attacks per secondValue in caps- Value in caps
Critical chance % multiplier- Critical chance % multiplierValue to weight ratio- Value to weight ratio
Critical damage- Critical damageSkill required- Skill required
Critical effect damage & duration- Critical effect damage & durationStrength required- Strength required
With all mods attached- With all mods attached
Weapon name (current weapon is highlighted)Damage per attack (damage per projectile)Damage per secondArea of effect damageBonus effectsAttacks per secondCritical Chance % multiplierCritical damageAction Point costDamage per action pointWeapon spreadMagazine capacity (shots per reload)Durability (number of attacks before breaking)WeightValue in capsValue to weight ratio
Drone cannon Mothership Zeta (add-on)40
466.7100Timed detonation3.33x150304.70.51417181999111.1
Drone cannon Ex-B Mothership Zeta (add-on)40
466.7100Impact detonation3.33x150304.70.51417181999111.1


In the southern area of the weapons lab, there is a room where one can use a nearby button to spawn-in brahmin for the drones to kill (not the room next to the shooting range, but the room next to the weapons cache). Enter the room and kill the drone for the weapon. There is also a second one in the same room that is automatically activated when the first is destroyed.