Night Stalker - Minigun
The Minigun is typically mounted at the firing points, just aft of the cabin, left and right.
The M134mm is an air-cooled, 6-barreled gatling gun with an effective range of 1000 meters.
It is carried on all armed Night Stalker helicopters.
The weapon can lay down a high volume of 7.62mmx51mm fire, ideal for suppressing large areas as the helicopters takeoff and land from LZs.
One downside of the M134 is that it is electrically-operated and relies on the aircraft's power system to drive it.
In the event of a power failure on the helo, the miniguns would be useless dead weight.
Many MH-47s carry a set of M240 belt-fed machine guns that are mounted at aft firing ports.