Gauss Cannon
From Halopedia, the Halo wiki
The Gauss Cannon is an anti-vehicle weapon usually mounted on a UNSC Warthog. It uses burst damage, unlike the continous damage of the chaingun. It is relatively powerful, also being known as the anti-vehicle Warthog. It uses the same Magnetic Accelerator technology as the orbital MAC gun defense system. It is, in essence, a pint sized version. It can kill infantry in one hit, two if they have an Overshield, and can destroy things most effectively. Due to its power, speed and manueverability, it is a good weapon against Wraiths.
This weapon uses a set of magnets used to propel a 25mm slug of depleted uranium, a very dense heavy metal, at high speeds. The raw mass and great speeds of the projectile is the key to the stopping power and performace of the gauss cannon. Unlike the chain-fed system of feed that the M41 machine gun uses, this cannon uses a tube to draw slugs from it's ammunition drum mounted below the cannon.
In Halo 2, this version of the Warthog seems to have replaced the M12A1 LAAV version of the Warthog, which featured three Rocket Launchers. That version became problematic due to the prodigous reload time necessary for the launchers.
