"If the Chaingun is relentless, the Chain Cannon is the right hand of oblivion. While not technically a cannon, it's been tooled for larger rounds and more damage, resulting in the popular if incorrect name." In Game Description
The Chain Cannon is a variant of the Chain Gun which deals about 20 more damage per round but has a slightly slower ROF. This trade-off does not significantly affect the overall DPS between the two weapons in skilled hands, although the Chain Cannon can deal more damage overall without reloading.