AIE-486H machine gun

The AIE-486H Heavy Machinegun is a United Nations Space Command ground weapon effective against infantry and vehicles.

Overview
The AIE-486H Heavy Machine Gun is a standard heavy weapon in use by the UNSC for dual offensive and defensive purposes. It seems to have replaced the UNSC's M247 GP Machine Gun turret, which was seen in Halo 2 carried into combat by Marines. For defensive purposes, it can be mounted on a tripod (M247 GP Machine Gun), but when used for assault, it can be detached from its tripod by a SPARTAN-II's brute force. In its unmounted form, while mobile, it has a limited ammunition capacity of 200 rounds and takes time to "warm up" before fully automatic fire, like a standard minigun.

The label of "heavy machine gun" most likely places this weapon in a category above 7.62mm ammunition. Due to the triple rotating barrels, as seen on the standard version of the warthog LRV, the AIE-486H HMG may very well use 12.7mm (.50in) cartridges, although this is unconfirmed.

Operation
The mounted turret is capable of fully automatic fire and has extreme defensive value as a mass generator of suppressive fire. However, the user's rate of elevation is low, there is a maximum angle of fire, and the user is stationary, exposed, and unable to react quickly to close-range scenarios. It has an infinite ammo capacity while stationary. It be operated by pressing the Right Bumper in the Halo 3 Beta.

Once on it, a SPARTAN-II can detach the turret and use it as a chaingun (done by pressing B). Once detached, the player will appear in a third-person view. The player also becomes slower due to the chaingun's weight. While wielding the gun in its standalone form (unmounted), you can't run or turn around quickly. If you are standing in one point you can aim slightly to either side before the Spartan adjusts his feet.

Pulling the right trigger (on the controller) once will cause the gun to fire two rounds at a moderate rate, while when you hold it down it builds up its rate of fire to a higher rate. It slowly climbs during automatic fire like the SMG, but because of its weight not as much. The gun cannot overheat like chainguns in other games.

Trivia

 * The AIE-486H Heavy Machine Gun, belonging to a new class of weapons known as support weapons, is one of the two current third-person view weapons. The other is the Missile Pod.
 * In the third-person view picture to the right, the HUD says that the secondary weapon is a Spiker. It's actually an Assault Rifle on the back of the Spartan. This is because you do not lose the 2 weapons you were carrying before obtaining the turret. Once you drop the turret, your primary weapon will be the Spiker and your secondary will be the Assault Rifle.
 * In the Halo 3 Beta, the AIE-468H HMG spawns on Valhalla by territory 2 and above the gate on High Ground.