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.
Despite the drawbacks, this weapon is truly devastating against lightly armoured opponents, particularly when using a belt of high explosive shells.
- Burst mode, varied shells, high stopping power, large clip capacity
- Using Incendiary Ammo, arguably best form of lighting for night missions in the game. I'd definitely choose this over electro flares!
- 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
- The damage per shot of the AC is significantly weaker than the Heavy Cannon counterparts.
- Ammo is also heavy, and comes in small clips. (14 I think) Takes up 2 spaces each too.
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.