Halo Alpha
Halo Alpha

The M68 Asynchronous Linear-Induction Motor, more commonly known as the M68 Gauss Cannon, is a weapon that fires hyper-velocity, high-density projectiles similar to those of a Magnetic Accelerator Cannon, except on a much smaller scale.[2][3][note 1] It can be mounted on a stationary stand, or on the rear of the M12G1 Warthog LAAV.



The M68 ALIM uses an asynchronous linear-induction motor to produce a bipolar magnetic field capable of launching a 25x130mm projectile at an incredible speed of just under Mach 40, or approximately 13,611.6 m/s. The speed of the Gauss Cannon's projectile in-game is much slower than its canonical speed of Mach 40. This is probably due to design and engine limits. The projectile moves more quickly in Halo 3 than in Halo 2. The great velocity gives the projectile immense kinetic energy, which is the key to the destructive power and performance of the Gauss cannon, giving it exceptional armor penetration.


The M68 ALIM is applied primarily in an anti-vehicle capacity by UNSCDF ground forces, though it can be used to devastating effect against infantry. It is often seen mounted on the Warthog in the same manner as the M41 LAAG, and while it does not possess the LAAG's extreme rate of fire, it displays near-pinpoint accuracy and overwhelming firepower, usually killing infantry targets with a single shot, and heavily damaging those in the immediate vicinity of where the round impacts. Its intended usage is similar to that of a 102mm SC-HE Rocket Turret, though the rocket turret does not possess the all-around utility and adaptability of the M68 ALIM.


The M68 is an extremely accurate weapon, useful against most enemy units. It has proven to be devastating against light-armored vehicles, it can take out a Ghost or a Banshee in one or two shots (depending on shot placement) and Wraiths in three. The M68 is also very deadly if used against infantry, however users should aim at the most dangerous units like Sangheili, Jiralhanae and Mgalekgolo in order to make full use of the weapon.


The M68 has a few disadvantages, mainly the weapon's slow fire rate. It is also quite difficult to use at long ranges, especially when shooting at moving targets, and can also be difficult to aim while the vehicle itself is in motion.

The Gauss Cannon can also cause permanent hearing damage when fired within 20 meters of unprotected infantry.[1]


  • The M68 is an excellent anti-vehicle weapon. It will get rid of enemy vehicles quickly. Usually it will take 1-2 shots to take out a Banshee, Ghost, Hornet, or Warthog, and 3-4 shots to take out a Wraith or Scorpion.
  • It is outstanding against Scarabs in Halo 3, since the Warthog on which the weapon is mounted is a smaller, faster target for it to hit. An effective tactic is to remain under the Scarab, avoiding the legs and the main gun, while your Marine gunner targets the Scarab's legs.
  • Experienced gunners using this weapon can effectively use the cannon's extremely high damage and accuracy to 1-shot kill most enemies. This has led to many players being able to attain high multi-kills and killing sprees, especially in multiplayer.


In Halo 2, the M12G1 LAAV variant of the Warthog replaces the M12A1 LAAV version of the Warthog, which was featured in Halo PC. The M12A1 LAAV became problematic due to the prodigious reload time necessary for the launchers, and the slow speed of the rockets themselves, although it did not appear in the campaign. A stationary version of the M68 (one of which triggers the flashback level Kizingo Boulevard) appears in Halo 3: ODST. The M68 can also be used near the start of ONI Alpha Site. In Halo Wars, the Gauss Turret is the final upgrade to the Warthog. It allows for much greater offensive and defensive capabilities.



  • In Halo 3, the screen on the cannon's firing mechanism will actually display its surroundings in real-time thermal imaging, similar to the scope of the Sniper Rifle System 99D-Series 2 Anti-Matériel.
  • A stationary version of the M68 Gauss Cannon as well as the M41 LAAG appears in Halo 3: ODST.
  • In Halo: Reach, the projectile will bounce off of surfaces if fired at a certain angle and can penetrate any object that has been spawned in forge excluding "glass" items. (Window Double, Glass Cover, Glass Sail, etc.)

Production notes[]

  • During the Halo 2 demo trailer, the Gauss fired at a fairly rapid speed. Later, in an early beta multiplayer phase, the M68 seemed to be slowed down. It was later revamped with its original rate of fire during the game's final stages.
  • The Halo 3 version of the Gauss Cannon is a bit weaker and has a slower rate of fire than its Halo 2 version.




  1. "While the Warthog gauss rifle is modeled as a magnetic acceleration cannon, the sound and effects are actually those of a railgun, which operates on a different principle. However, the sound and effects were so cool that we couldn't not use them."
    — ferrex providing additional information about the M68.