M68 Asynchronous Linear-Induction Motor

The M68 Gauss Cannon is a weapon that fires hyper-velocity, high-density projectiles similar to those of a MAC gun, except on a much smaller scale. It is mounted on the rear of the M12G1 Warthog LAAV.

It is very powerful and very useful against vehicles. However, it is not as effective against infantry as the M41 LAAG, which is also mounted on the Warthog. This is because there is little splash damage and it has a slower rate of fire, but a direct hit will kill most enemies in one shot, two if they have an overshield. Due to its power and reasonable rate of fire it is a good weapon against Wraiths and many other vehicles. It is similar to the 102mm SC-HE Rocket Turret of Halo PC but shoots like a miniaturized version of the MAC cannon.

This weapon uses an Asynchronous Linear-Induction Motor to produce a bipolar magnetic field capable of launching a 25mm x 130 projectile at hyper-sonic velocities. The great velocity of the projectile is the key to the stopping power and performance of the Gauss cannon, giving it exceptional armor penetration.The devastating effects of the M68 Gauss Cannon can also stretch to enemy moral by eliminating The Covenant ground leaders like Elites, Brutes and enemy ground vehicles and leaving helpless and demoralized Grunts and jackals hopelessly fighting or scattering in fear.

In Halo 2, this version of the Warthog seems to have replaced the M12A1 LAAV version of the Warthog, which featured a triple barreled rocket launcher. That version became problematic due to the prodigious reload time necessary for the launchers, and the slow speed of the rockets themselves, although it was not actually in the campaign. In Halo 3: ODST there appears to be a gauss cannon turret.

The Gauss Warthog made its debut in Halo 2 and returns in Halo 3.

The predecessor to the M68 Gauss Cannon was the M66, the primary armament of the Cobra artillery vehicle seen in Halo Wars. The M66's were much larger and bulkier, though they made up for this by being able to fire heavier rounds.

Trivia

 * While operating on a similar principle to the M99 SASR, the shells for the M68 appear to be designed to cause hypervelocity collisions, where the target and slug get almost entirely vaporized on impact. This is probably intended to reduce over penetration.
 * During the Halo 2 demo trailer, the Gauss was shooting at a fairly decent speed. Later, in an early beta multiplayer phase the Gauss seemed to be slowed down and also seemed to have lost all of its hype. It was later revamped to its original rate of fire during the game's final stages
 * In Halo 3, the slug in mid flight is blue with a blue tail, making it look like Covenant weapon's fire at first glance. This 'blue light' is most likely the slug heating the air around it to super heated levels due to friction with the atmosphere.
 * The Halo 3 version of the Gauss Cannon is weaker and has a slower rate of fire. This came in to balance, since Halo 2 Gauss Cannon was too powerful in-game, though it is still devastating in combat.
 * Ferrex said in a thread, "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."
 * In the Halo 3: ODST gameplay trailer on the Xbox Live Marketplace, footage of a mounted version of the Gauss Cannon has been shown.
 * It's featured as an EMP cannon in the popular web series Red vs. Blue
 * In an interview with Nathan Fillion, there is a unmounted Gauss cannon seen during a short gameplay montage being shown.
 * It is possible that the M68 Gauss Cannon was developed by UNSC leaders to be give The Covenant a firsthand demonstration of MAC weapons and to be cost effective.
 * Occasionally the M68 Gauss Cannon can be used as Anti Aircraft Gun against Banshees, this is however rare, as the M68 Gauss Cannon was made as an anti armor weapon.
 * As this weapon is considered the smallest known MAC gun in the Halo universe it shows that the MAC family can be "Small But Deadly" or in this case "Smaller But Deadly".