Fat Man (Fallout 4)

The M42 Fat Man is a weapon in Fallout 4.

Characteristics
First entering service in September 2077 with the U.S. Army, the Fat Man is a shoulder mounted mini nuke launcher. The variant appearing in Fallout 4 has a slightly different appearance than in previous games. There is no longer a handle on the right side of the launcher, and instead two straight handles on the bottom. It also appears to be larger, with a rusted silver paint job.

Developers struggled to find a way to fire the heavy ammunition from a man-portable system far enough to keep the operator outside the blast radius, losing a lot of people in the process. Eventually, it was discovered that by placing a small sub-charge into the ammunition itself, similar to bullets being fired from a gun (or perhaps more accurately described as being along the lines of a recoilless launcher), the warheads could be launched a considerable distance without adding too much weight to the already heavy weapon.

When fitted with the MIRV launcher, it fires six mini nukes in a cluster that separate in mid-air, drastically reducing its range, but increasing its overall damage and area of effect.

Variants

 * Big Boy, a unique version with the Two Shot legendary modification.
 * The Striker, a unique version that fires modified bowling balls instead of mini nukes.
 * Nuka-nuke launcher, a unique version that deals 50% more damage than the standard model by firing quantum-enhanced Nuka-nukes.

Locations

 * ArcJet Systems - Found in the room marked '2' in the Engine core.
 * BADTFL regional office - In the evidence locker.
 * Boston Airport - Slightly north of Boston Airport, there are wrecked cars. Inside one is a Fat Man. From the Boston Airport fast travel location, head east. The nose section of an airplane will be in front of you. The Fat Man is located in a van on the water's edge behind the nose section.
 * Boston mayoral shelter - Beneath the basketball court is an entrance to a cave. The Fat Man lies next to a dead soldier at the end of the cave. There is a nearby deathclaw that will attack on sight.
 * Cabot House - In the basement near Edward's bed.
 * D.B. Technical High School - At the far end of the old swimming pool in the northwest corner of the lowest level of the school. This is by the raider boss' bed and terminal.
 * Federal ration stockpile - In the main stockpile area, just inside the room with two turrets against the wall near the terminal that operates the doors ( the second one). This Fat Man also respawns.
 * Fort Hagen - In the armory.
 * Goodneighbor - Found behind the desk, beside KL-E-0 in the Kill or Be Killed store.
 * Gunners plaza - In a locked utility closet in the southwest corner of the second floor.
 * Hub City Auto Wreckers - Carried by a named Gunner, Bridget.
 * Lexington - On the walkway where the Raider with the power armor is found.
 * Libertalia - Carried by a random raider at the top of the main building.
 * Malden center - Found behind a train car hugging against a wall.
 * Quincy ruins - being held by Sergeant Baker, who is located on top of the church in the ruins.
 * Revere satellite array - Can be found at the top of one of the towers, next to a power armor frame and a case with miscellaneous ammo and other items.
 * Robotics Disposal Ground - Found laid on top of a car hood near the back of the scrapyard.
 * Salem - On a shelf in a bombed out store across from the chapel.
 * Spectacle Island - On the lower level of the beached tugboat containing the generator.
 * The Castle - Found in the armory on a shelf, next to it will be a mini nuke.
 * The Prydwen - Inside Proctor Teagan's store.
 * Zephyr Ridge Camp - Carried by a trapper on the tower's top level.

Behind the scenes
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 * "Fat Man" was the codename for the plutonium atomic bomb that was detonated over Nagasaki, Japan on August 9, 1945. With the exception of the tail fins, the mini nuke has a striking similar look to Fat Man.
 * The Fat Man may have been inspired by the real life M-28/29 "Davy Crockett", which was deployed with American soldiers in the Cold War. The main differences are that the Davy Crockett was fired via tripod, while the Fat Man is shoulder-fired, much smaller/lighter and its mini nukes have a significantly smaller yield than the Crockett's.
 * The Fat Man could only exist in its form if it used the Isotope Californium-252, due to its low critical mass, which is the mass necessary to start a nuclear fission reaction. Though it would have been incredibly expensive to mass produce them since a microgram (one millionth of a gram) of Californium 252 costs 10$ and you would need around 2.73 kilograms (5.95 pounds) per mini nuke.
 * Additionally, Since the half-life of the 252 isotope is only around 2.64 years, any Mini-Nuke found to have existed from the Pre-War Era would be useless. By the time the Sole Survivor would find them, the isotope in the Mini-Nuke would have it's radioactive mass cut in half around 79 times. After only 20 years of sitting, the Mini-Nuke would have less than 1% of it's explosive potential (Likely not enough to cause a chain-reaction). After 210 years, the mass would be 1.65E-24 percent of it's original value. instead one would have around 2-3 kilograms (Around 6 pounds) of Curium-248, which is far below the 40kg (near 90 pounds) needed for critical mass of that element