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These autocannons use electromagnetic asynchronous linear-induction motor (ALIM) technology to fire hyperdense projectiles at velocities unmatched by chemical energy-based weaponry.
Numerous starfighters in service with the UNSC are equipped with machine-linked autocannons. These include exoatmospheric craft like GA-TL1 Longswords, YSS-1000 Sabres, F-41 Broadswords, and even suborbital bombers like the B-65 Shortsword. Several models of the autocannon exist, while the calibre of the rounds ranging from 30mm to 50mm. The autocannons are very effective in engaging hostile spacecraft, such as Phantoms and Type-31 Seraphs.
M9109 ASW/AC 50mm
The GA-TL1 Longsword fighter is equipped with eight M9109 coilguns that fire 50mm projectiles at such speeds that they immediately begin to burn up from air friction when fired within an atmosphere. They are often used in an air-to-surface combat capacity during tactical strikes. The Longsword's autocannons are very effective against Covenant Type-31 Seraph.
M8545 ASW/AC 40mm
When their advanced stealth system fails them, Winter-class prowlers are equipped with twin M8545 autocannon.Lightly armed, these autocannons are only a last resort as the prowlers are designed to evade and escape threats.
M1075 ASW/AC 35mm
The F-41 Broadsword fighter is equipped with two rapid-fire M1075 autocannons. The autocannon is not rigidly attached to the fighter's hull, but is on retractable, semi-articulated armatures. The versatility of these autocannons allows it to target hostiles with ease. It is very powerful, being able to effectively eliminate Forerunner weaponry, such as Z-8250 light artillery.
M1024 ASW/AC 30mm
Two M1024 cannons are mounted on the YSS-1000 Sabre as its main armament. The Sabre is armed with two cannons, one on each wing, situated close to the cockpit. The cannons fire 30mm rounds that travel slowly and requires the pilot to lead the shots. The cannons are very powerful and can take out a Banshee in one or two shots and can quickly take out a Type-31 Seraph starfighter's shielding, leaving it vulnerable to homing missiles.
M955 ASW/AC 30mm
The B-65 Shortsword is equipped with several M955 autocannons that fire 30mm projectiles. The autocannons complement the Shortsword's M/RODAS delivery system, allowing it to engage hostile aircraft.
The novel Halo: Shadows of Reach establishes that the M1075 model autocannons installed on the F-41 Broadsword can fire their projectiles with a velocity of one-tenth the speed of light. This number is incredibly dubious, given the energy needed to support such acceleration. When asked on Twitter, Shadows of Reach author Troy Denning later clarified that this number should be considered hyperbole until further comment from 343 Industries, additionally adding that he would consider the muzzle velocity of these weapons more in line with existing smaller-scale magnetic weapons such as the M99 Stanchion.
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