Minigun (Fallout 3)

The Minigun in Fallout 3 is the most commonly-encountered Big Gun, which means it is comparatively easy to find and repair, as well as one of the few Big Guns easy to find ammunition for; nearly every Super Mutant Brute encountered with one has at least 30 5mm Rounds for it. It is also carried extensively by Brotherhood of Steel units, Brotherhood Outcast Units, Enclave Soldiers, as well as occasionally on some Raiders and Slavers. This is offset somewhat by the Minigun's high rate of fire quickly using up ammo. Though it does use up ammo as quick as the Gatling Laser, the Minigun is designed as a sustained-firing weapon, and its rate of fire of 20 rounds per second means that it can use up 240 rounds quickly. Because of this, those who intend to make use of it should buy additional ammunition, which is generally quite plentiful at shops.

When firing the Minigun without V.A.T.S., there is a wind-up time between holding the fire button and when it actually fires. It usually takes under a second to begin shooting. This can be negated by tapping the fire button repeatedly to keep it spinning while not actually firing.

Design
The Minigun in Fallout 3 would seem to be based on the XM214 with similarities in feed mechanics such as the use of a "Cassette" ammo box. Both were man portable though the XM214's mechanical components seemed to be more tightly grouped. Also, the XM214 was primarily designed as a vehicle-mounted weapon, although it's highly adjustable fire rate allowed it to be set slow enough to control when firing by hand. The Fallout 3 Minigun appears to be designed primarily as a man-portable weapon, that is, it is designed to be fired in the hands of it's user, not as a mounted weapon. It is very light weight for such a weapon, most belt-fed light machine guns weigh at least 20 pounds unloaded and the XM214 minigun from which it is similar weighs 25.5 pounds by itself, and 36 pounds with the drive motor and the side stripping feed mechanism not to mention the weight of the ammo (not a concern in Fallout 3 since ammo is weightless).

Unique Minigun
There is a unique Minigun called Eugene which is available as a reward for Reilly's Rangers and has notably better firepower. Due to the ability to get Ranger Battle Armor through a trick and the difficulty of picking Brick's pocket, Eugene is arguably the better of the two rewards for that quest for those prepared to exploit the game.

Appearances
This Minigun variant appears only in Fallout 3