M651 missile launcher
From Halopedia, the Halo wiki
The Class-2 Guided Munition Launch System[1] is a United Nations Space Command aerial vehicle-mounted weapon system.
The Hornet is equipped with two of these launchers, and each weapon system is believed to encompass a missile launcher and a machine gun. It fires armor piercing "gattling" rounds at a very high rate. Fires high explosive missiles similar to a banshee's Fuel rod bomb[2].
