A heavier version of the Machine Gun, Chain Guns are exclusive to the Back Weapon.
Designed to lay down an impressive amount of firepower, Chain Guns have the single shot damage of rifles but have the rapid fire nature of Machine Guns. This makes extended use cost prohibited but their DPS can be amazing.
In Armored Core 2, these weapons fire slower but with Heat, they can cause an AC to overheat rapidly. This means that they can quickly overheat a target and cause their AP to drop even faster.
With the rebalances that Nexus provided, Chain Guns were given magazines, like their Machine Gun counterparts.