Minigun

The Minigun is a mounted Machine Gun that appears at certain points of Call of Duty 4: Modern Warfare, Call of Duty: Modern Warfare 2, Call of Duty: Modern Warfare: Mobilized, Call of Duty: Black Ops and Call of Duty: Modern Warfare 3.

Call of Duty 4: Modern Warfare
In Call of Duty 4, the Minigun is used by Soap in "Heat" to provide supporting fire for his retreating SAS allies. The Minigun is attached to a downed helicopter (the same helicopter can be seen in the same position in "Safehouse", but the minigun is not present) just past the church. It can also be found in FNG, but the player will not be allowed to use it, since it will just be laying in the weapon's cabinet.

The Minigun can really do a lot of damage because of its high firing rate, but it needs to be spooled up and can overheat. However, keeping it spooled will not overheat the gun. It's also worth noting that the minigun is highly effective against the helicopters in the mission "Heat", it can normally down one in a short burst and will stop the troops getting off and engaging the player later on in the mission. On Arcade Mode, a helicopter kill is worth 1000 points. A quick spray around will down them all very quickly.

Call of Duty 4: Modern Warfare (DS)
The Minigun is constantly used throughout the Helicopter levels in the game, where the player usually needs it to eliminate opposition or take out objectives. Unlike its console counterparts, it cannot overheat and does not need to be spooled up before firing, making it an extremely effective weapon. However, it does lack power and is somewhat inaccurate.

Call of Duty: Modern Warfare 2
The Minigun returns in Modern Warfare 2. It is featured far more often than in Call of Duty 4 and also now has a much shorter and more realistic spooling time. It can be seen in the single player mission "Team Player" mounted on a Humvee. It is also seen on various helicopters.The new Sentry Gun, available in the campaign, Special Ops and Multiplayer, also uses the M134. Additionally, in the mission "The Enemy of My Enemy", it is seen mounted to black SUVs used by Shadow Company.

The M61 Vulcan replaces the M134, being mounted on a Blackhawk, in Of Their Own Accord and in the Spec Ops Mission Big Brother using 20mm Explosive Rounds.

The HMMWV-mounted M134 is far more inaccurate than the other implementations, firing in a wide, but consistent circular spread; the miniguns mounted on helicopters fire with a much tighter spread.

In Multiplayer, the minigun appears in the multiplayer maps Skidrow, Wasteland, Karachi, Rundown, and Overgrown, replacing the M249 as the standard stationary gun due to balancing issues, due to players in Call of Duty 4 constantly going prone, shooting off a burst, then going prone again automatically due to the way the game handles it. Now, players have to expose themselves for the short spool time before being able to shoot, however the minigun has a higher rate of fire to make up for this. It can be devastating at controlling choke points but the gunner is very exposed and will be a target for enemy snipers.

Using the aim function zooms in and spools the gun barrels without firing, eliminating the "warm up" time. The word "GAU 4" can be seen on the top.

Call of Duty: Modern Warfare: Mobilized
The minigun reappears in Modern Warfare: Mobilized as a usable support weapon. Like in the previous Nintendo DS game set in the Modern Warfare era, it can only be used in helicopter levels. Unfortunately, the only helicopter level is "Helicopter Insertion", so its use is limited. It is now much more powerful, though not as powerful as on the consoles and PC. Luckily, its accuracy has been increased by a large amount, allowing nearly all of the bullets to focus on the designated target, compensating for its low damage (for a minigun).

Call of Duty: Modern Warfare 2: Force Recon
The minigun appears in Force Recon as a support weapon used by the player. Like in NDS installments, it is only used in helicopter based missions.

Call of Duty: Black Ops
The Minigun returns in Black Ops, and is used as one of the helicopter's weapons in Redemption. The minigun is also used in the Chopper Gunner. The minigun is not able to be used directly as a stationary platform, but can be used when mobile by use of the Death Machine.

Call of Duty: Modern Warfare 3
The M134 returns in Call of Duty: Modern Warfare 3.

Campaign
In the end of the mission "Black Tuesday", a M134 is mounted on a UH-60 Blackhawk and was manned by Frost to defend the helicopter from three enemy Mi-24 Hinds. Frost later uses one mounted on Rhino 2 in "Goalpost", after Rhino 2's gunner is killed.

Multiplayer
In the multiplayer map Bakaara, there is a mounted minigun on the crashed UH-60 Blackhawk located near the port area. Miniguns are also seen scattered throughout Liberation.

Trivia

 * The minigun uses the same reticle as the original game's MG42.
 * In multiplayer, if the player uses a mounted minigun while wielding any sniper rifle, the player can hold their breath while zoomed in with the minigun. However, while it does not affect the player's accuracy, it does remove the minimap from the corner of the screen.
 * If a player is using a class set up with One Man Army, there is a glitch where a player can use the perk to switch to a class with a riot shield and during the switch can use the Minigun, but once complete the player will have a riot shield in front of them as they operate the weapon.
 * A glitch has been discovered that involves the FGM-148 Javelin. The glitcher equips the FGM-148 Javelin and uses any Minigun. The glitcher then spins the barrel using the zoom button, and the Javelin lock-on sound is heard. The glitcher then fires and a Javelin rocket is emitted. The rocket travels way further than normally, and, if used correctly, it is possible to shoot a rocket across the whole map of Wasteland.
 * If the player does not get off the minigun in "Heat" when Captain Price orders him to, an enemy grenade will be thrown directly where the player is and will blow them up.
 * In Call of Duty: Modern Warfare 2 multiplayer and Call of Duty 4, there is no hand on the minigun in first person.
 * In Call of Duty: Modern Warfare 3 multiplayer, if you aim in on the minigun with the XM25 equipped, the XM25's HUD will show up and still show range, but not mark.
 * In Bakaara in Call of Duty: Modern Warfare 3, the gun model on the crashed helicopter is lifted directly from Call of Duty 4