GAU-23/AW/Linkless Feed Autocannon
From Halopedia, the Halo wiki
The GAU/23 is a tri-barreled autocannon found equipped on many UNSC aircraft. It is capable of engaging a number of enemy units of various types, ranging from infantry, to armored vehicles and aircraft. The version mounted on Sparrowhawks can fire the full range of 20mm aircraft ammunition, though the standard loadout is either M718 SAPHEI or PGU-42/B API, with a depleted uranium core.
When mounted on certain variants of the AV-14 Hornet, the GAU/23 is mounted on the craft's chin as a rotary cannon. Two of the weapons can be mounted on the wingtips of the Sparrowhawk, while the AC-220 Vulture can host four wing-mounted guns.
During the early Human-Covenant War, the GAU/23 was mounted on variants of the AV-22 Sparrowhawk, AV-14 Hornet and AC-220 Vulture gunships employed by the UNSC Spirit of Fire during the Harvest campaign, Battle for Arcadia and Battle of Trove.
There is discrepancy among sources as to the GAU/23's ammunition type. The Halo Wars: Official Strategy Guide makes note that the GAU/23 fires .50 BMG ammunition, which would make it 12.7×99mm Armor-Piercing ammo similar to that used by the M41 Vulcan. The later Halo: The Essential Visual Guide indicates the weapon to fire 30mm ammunition, while a later Halo Waypoint Canon Fodder post focusing on the Sparrowhawk identifies the ammunition type as 20mm. This article assumes the latter source as definitive information.
Additionally, the described properties of the GAU/23 as seen on the Sparrowhawk and Hornet in Halo Wars do not match the appearance of the weapon used by the Vulture gunship. The former two aircraft use the GAU/23 as a tri-barrelled autocannon for light targets, while the Vulture appears to only have one barrel per weapon firing at a slow rate of fire.
List of appearances