Experimental MIRV

The experimental MIRV is a weapon in Fallout 3.

Characteristics
The experimental MIRV is a unique Fat Man that can be found in the bomb shelter area of the National Guard depot. This weapon deals the most damage of any weapon in the entire game, as it acts like a shotgun version of the Fat Man, delivering eight mini nukes at once. The MIRV actually does the same damage as a Fat Man per mini nuke, as 12 880/8 equals 1 610. It will not fire if the Lone Wanderer doesn't have at least 8 mini nukes in their inventory to load it with. If they have fewer than 8 mini nukes, the weapon will reload but never discharge the payload.

Durability
The Experimental MIRV can fire a total of 63 shots, the equivalent of 504 mini-nukes, from full condition before breaking.

Variants

 * Fat Man - The common variant in Fallout 3.

Location
The player must complete the unmarked quest Keller Family Refuge before they can gain access to the secure section of the depot housing the weapon, though it's also possible to gain entrance to the armory by using a glitch. See the bugs section on National Guard depot for more details.

Behind the scenes
MIRV is a military term for Multiple Independent Reentry Vehicle. It is a collection of nuclear weapons carried on a single intercontinental ballistic missile. Using a MIRV warhead, a single launched missile can strike several targets, or fewer targets redundantly.

Bugs

 * Sometimes a graphics error can occur when detonation is very close. It can cause large, black rectangles to extend from the weapon out to as far as you can see. A console restart will fix this.
 * Sometimes when lifting the item, it will twirl around in the air.
 * If you equip the weapon and enter V.A.T.S. while having less than 8 Mini nukes, V.A.T.S. will not show you the "not enough ammo" box, but if you actually try to use it the weapon will not shoot and you will get stuck in the V.A.T.S. sequence, reloading a save will fix the problem.
 * There is an extremely rare chance, that a Fatman with the Experimental MIRV modification will spawn in a safe, this is likely an unexplained bug as the Creation Kit shows no indication of the Experimental MIRV implemented onto any leveled loot lists.