Minigun A minigun is a multi - barrel machine gun with a high rate of fire , employing Gatling - style rotating barrels . It was a standard military weapon before the Great War , with Rockwell ' s CZ series being the most popular choice in the United States . It is widely used by many factions such as the super mutant s , Brotherhood of Steel and the Enclave , due to its extraordinary firepower at close range . Models . CZ53 personal minigun . < section begin = " CZ53 " / > A Rockwell CZ53 personal minigun is capable of firing 5mm ammunition at over 60 , 000 RPM with an ammo capacity of 120x 5mm round . The CZ53 personal minigun makes up for the small 5mm round by sending a hail of bullets toward its target . Its sheer size , coupled with its trademark sound , is enough to send anyone in its path running for cover . It ' s a great weapon for suppressing fire , letting others flank the unsuspecting enemy . When the Great War struck , it was already an aging design and was slowly being replaced by the more advanced CZ57 Avenger minigun . Later models of the CZ53 have six barrels linked into pairs , with four barrels on top and two on the bottom , a cage underneath the weapon to hold an ammo box containing 240 5mm rounds , and used in combination with a backpack . The first model was the favorite weapon of the Mariposa super mutant s during the Unity ' s time , and allowed most or all of the super mutants to wield them effectively with only one arm . < section end = " CZ53 " / > 5mm CZ57 Avenger minigun . < section begin = " CZ57 " / > Rockwell designed the 5mm CZ57 Avenger as the replacement for their aging CZ53 personal minigun . The Avenger ' s design improvements include improved gel - fin cooling and chromium plated barrel - bores , giving it a greater range and lethality . It also has an ammo capacity of 120x 5mm round like the earlier versions of the CZ53 model . Later models of CZ57 have a high - speed motor , a cage underneath to put the ammo box and used in combination with a backpack . < section end = " CZ57 " / > 4 . 7mm Vindicator minigun . A Rheinmetall AG 4 . 7mm Vindicator minigun firing 4 . 7mm ammunition at over 90 , 000 caseless shells per minute down its six carbon - polymer barrels , and with an ammo capacity of 100x 4 . 7mm round . K9000 cyberdog gun . This weapon is actually an odd form of cyberdog , except instead of a robotic body in the image of a canine companion , a living dog ' s brain has been provided with a machine gun frame , utilizing . 357 Magnum ammunition . Its " canine " features include two metallic " ears " mounted on top of the weapon that move like a real dog ' s , and a sniffer mounted on the jar containing its preserved brain , allowing the gun to sense its surroundings . The metal ears also appear to move up and down faster if the gun is pointing in the direction of an enemy . FIDO . FIDO is another variation of the cyberdog gun . Unlike the K9000 cyberdog gun , FIDO uses instead of . 357 Magnum rounds , resulting in higher damage and a slightly higher spread . The brain case and the scope are red instead of green and the decal is changed from a golden retriever to a bulldog . Other features of the K9000 cyberdog gun are included in FIDO . Shoulder mounted machine gun . The shoulder mounted machine gun is similar to the minigun , but with a slower rate of fire and the bulk of the weapon resting on the user ' s shoulder . This weapon utilizes 10mm rounds and has a moderately high strength and skill requirement . 5 . 56mm CZ57 Avenger minigun . A variant model of the regular CZ57 Avenger minigun seen in the Midwest which is more compact , completely black , less powerful and chambered for 5 . 56mm bullets with an ammo capacity of 120x 5 . 56mm round . 7 . 62mm Vindicator minigun . A variant model of the regular Vindicator minigun seen in the Midwest with a completely new design , a display screen that show the remaining ammunition and chambered in 7 . 62mm bullets with an ammo capacity of 100x 7 . 62mm round . MEC Gauss minigun . An extremely rare minigun , the MEC Gauss minigun was designed by the Chinese . Atypical for an automatic weapon , it uses Gauss technology , multiple electromagnetic fields to firing 2mm ammunition at over 90 , 000 rounds per minute to relativistic velocities , with an ammo capacity of 80x 2mm round . Vault - Tec minigun . < section begin = " Vault - Tec 9mm minigun " / > A post - War minigun designed by Vault - Tec in the Secret Vault . The Vault - Tec minigun has a lower rate of fire than a general minigun but , unusually for a minigun , chambered in common handgun ammo . It has five barrels and it was used by the Attis army in Texas . < section end = " Vault - Tec 9mm minigun " / > CZ25 military minigun . A Rockwell CZ25 military minigun firing . 223 ammunition with an ammo capacity of 54x . 223 round . A multi - barreled weapon capable of firing large quantities of ammo with minimal heat issues .