The Point-Defense Gun functions much like the CIWS designs created during the 20th Century, firing 50mm projectiles. Unlike Archer missiles and the MAC weapon systems mounted on capital ships, the Point-Defense Guns are not used to engage Covenant capital ships in ship-to-ship combat (The only known case is in Halo: Reach level Long Night Of Solace), but is instead meant to take out smaller threats like Seraph fighters or boarding craft to prevent (or at least lessen) the damage inflicted on a warship.
Because human operators lack the reflexive responses necessary to operate the point-defense guns to maximum effect, the autocannons are computer controlled and, if an AI is available, control is diverted to it. "Smart" AI's seem better able to operate the Point-Defense Guns than standard computers and also lesser "dumb" AI's.
In Halo: Reach Point-Defense Guns can kill a player with a single shot if it hits the player.
During the human occupation of Installation 04, the ODSTs that recaptured and secured the wreckage of UNSC Pillar of Autumn from the Covenant managed to scavenge several dual barreled 50mm turrets. The ODSTs utilised the scavenged defense weapons and used them as anti-air defensive emplacements at Alpha Base.
- M870 Rampart 50mm Point Defense Guns - lower and narrower in profile than the M910, it was mounted on Charon-class light frigates.
- M965 Fortress Point Defense Guns - Prototype 70mm guns mounted onboard UNSC Infinity
- M910 point defense network - Used on UNSC Pillar of Autumn, Autumn-class heavy cruisers and Paris-class heavy frigates.
- ↑ 1.0 1.1 Halo: Evolutions - Essential Tales of the Halo Universe - The Impossible Life and the Possible Death of Preston J. Cole, page 475
- ↑ 3.0 3.1 Halo: The Flood, page 215
- ↑ Halo: The Fall of Reach, page 272
- ↑ Halo: The Flood, page 137
- ↑ https://blogs.halowaypoint.com/en-us/blogs/headlines/posts/the-halo-bulletin-101012-