The Vault - Fallout Wiki

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The Vault - Fallout Wiki
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This is a lore summary, presenting intradiegetic or in-universe information about the subject. For game characteristics and similar data, consult the table on the right.
Game-specific articles
Fallout 3Fat Man
Experimental MIRV
FO: New VegasFat Man
Gun Runners' ArsenalEsther
Fallout 4Fat Man
Big Boy
Experimental MIRV
Fallout 4: FHThe Striker
Fallout 4: NWNuka-Nuke launcher
Fallout 76Fat Man
Experimental MIRV
Fallout ShelterRusty Fat Man
Fat Man
Enhanced Fat Man
Hardened Fat Man
Guided Fat Man
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The Fat Man is perhaps the most devastating infantry weapon ever unleashed upon the modern battlefield - a hand-held catapult that launches portable nuclear bombs.

Fallout 4 loading screen hints

The M42 "Fat Man" Launcher[1] is a shoulder-fired, catapult weapon system that launches tactical nuclear ordnance, the "mini nuke". It appears in the following games: Fallout 3, Fallout: New Vegas, Fallout 4, Fallout 76, and Fallout Shelter.


The M42 Fat Man was developed at Fort Strong near Boston, Massachusetts. Development began in February 2076, with the goal being the development of a man-portable tactical nuclear launcher easy enough for use by troops on the ground, to destroy reinforced and entrenched positions.[2][3] Problems manifested instantly, as warheads were simply too heavy to clear the blast radius fast enough to provide safety for the operator. Even stripping them to the minimal possible size failed to produce an acceptable effect. Instead, the development team decided to increase the power of the launcher unit, even considering using railgun technology to accelerate the warhead. The notion was largely academic, as it would require for the overburdened soldier to carry an additional power pack the size of a suitcase and turn the Fat Man into a crew-served weapon.[4] Concurrent development ran on the MIRV version of the launcher. Live-fire testing claimed lives, in fact, with two soldiers killed during a test. No remains were recovered and the commanding officer in charge of the project, General Brock, covered up the incident, ordering his subordinates to send sand packed in an urn to their relatives.[5]

The project hit a breakthrough in December 2076,[6] when the project lead discovered a solution for the launcher problems. Six hours, fourteen cups, and one concerned night shift lab crew later, the future M42 launcher was conceptualized: Based on the spigot mortar mechanism, the launcher would only have to accommodate a firing through and system, relying on mechanical launching, rather than chemical or electrical means. Much like the 130 year old PIAT launcher, the Fat Man warhead would be propelled by a sub-charge embedded inside the warhead, "catapulting" the warhead through the air to the target - giving plenty of range with the added bonus of not producing a smoke trail that could reveal the firing team to the enemy.[7]

By September 2077,[8] after one hundred test firings the weapon were complete and ready to be shipped to units overseas. A large number of units was manufactured and shipped together with the appropriate warheads to select locations throughout the United States.[9]


Fat Man

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The standard M42 "Fat Man" Launcher is a man portable nuclear payload, anti-materiel weapon platform. It can contain a single mini nuke only.

Experimental MIRV

Fat Man.png

Named for the multiple independently targetable reentry vehicle (MIRV) ballistic missile payload, this variant of the M42 "Fat Man" Launcher fires eight mini nukes at once, arguably making it overkill for any application due to its more plentiful payload and larger spread.


Gameplay article:

Esther is a unique M42 "Fat Man" Launcher with a different rear mechanism, a blast shield, a light-blue body, and a thick glass or plastic bed holding the mini nukes. It weighs 10 pounds more than a standard M42 "Fat Man", but does not jam, and protects the user from damage.

The Striker


Gameplay article:

The Striker was the invention of the employees of Beaver Creek Lanes for Thomas Davis, a former league champion that became paraplegic after sustaining an injury in the Sino-American War. The Striker was meant to serve as a tool for Davis to launch modified bowling balls so he could still enjoy bowling. Bowling balls are the only ammunition this modified fat man can take.

Nuka-nuke launcher

FO4NW Nuka Nuke Launcher.png
Gameplay article:

A unique Fat Man hidden by John-Caleb Bradberton, the inventor of Nuka-Cola in Nuka-World. Instead of throwing regular mini nukes, it instead launches Nuka-nukes, a specially modified, quantum-enhanced mini nukes.

Behind the scenes

  • The names of Fat Man and Little Boy are references to the code names of the atomic bombs dropped by the United States on Japan during World War II: Little Boy was dropped on Hiroshima while Fat Man was dropped on Nagasaki. For this reason, the weapon's name has been renamed as the Nuka Launcher in the Japanese translation of both Fallout 3 and Fallout: New Vegas due to its relation to Japanese history. However, the Little Boy modification still retains its name.
  • The bell heard after reloading is actually the lunch bell at Bethesda.[10]
  • The designation M42 is shared with a couple of other pieces of military equipment, such as the M42 Duster SPAA gun and the M42 submachine gun.
  • The M42 Fat Man is similar to the real-life M-28/M-29 Davy Crockett miniature nuclear launch device.



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