M370 autocannon

The 70mm Chin Mounted Chain Gun is an anti-personnel/anti-vehicle weapon mounted below the front of a Pelican dropship or at the rear section where troops offload.

Overview
The gun is linked to the movements of the pilot's head, which allows for very short delays between spotting enemies and firing, the turret will rotate up to 1222120 degrees to wherever the pilot is looking. However, the turret can also be operated by a copilot, or manually by a gunner.

This weapon fires very large 70mm shells. The rate of fire is most likely lower than most UNSC automatic weapons, but damage per hit is likely to be very high to compensate. A variety of ammunition is most likely compatible with this weapon. High-explosive rounds are probably used as standard. It should be noted that the nose-mounted machine gun featured on Halo 2's Pelican dropship is not this weapon. That turret is simply a variant of the M247 General Purpose Machine Gun (GPMG).