M340 autocannon

The 40mm chain gun is an anti-personnel/anti-vehicle weapon mounted on the nose of some D77-TC Pelican dropships. It was apparently replaced in service by the 70mm chain gun which was common prior to 2525. Like other nose-mounted weapons used by Pelicans, the chain gun is likely linked to the movements of the pilot's or co-pilot's head, or manually by a gunner.

List of appearances
Halo: The Fall of Reach