This is the automatic version of the Heavy Cannon. It retains the versatility of the Heavy Cannon and features a larger magazine as well as the capability for automatic fire.
Drawbacks worth noting:
- 1. To compensate for the larger clip capacity, the bullet calibre has been reduced slightly.
- 2. To prevent the weapon from overheating, the Auto Cannon's rate of fire is greatly reduced in burst mode.
- 3. The Auto Cannon is much heavier than the Heavy Cannon, which also makes it slightly harder to aim with.
Pros: Burst mode, varied shells, high stopping power, large clip capacity
- Very heavy, very slow burst mode
- AC-AP, Standard Rifle, and Standard Pistol ammo cannot damage XCOM Power Armor or Cyberdisk
- Auto shot takes a third longer than HC snap-shot
Notes:  This is true. The Auto Cannon is the slowest auto-fire weapon in the entire game. It's also the 2nd least accurate burst mode.