Heavy cannon

The heavy cannon is a multi-purpose automatic rifle which occurs as a weapon in Doom Eternal, replacing the heavy assault rifle from the previous game, with some changes to the modifications and upgrades, although they both function similarly. It is introduced in Hell on Earth, after the second demon encounter.

"Precision weapon, making it good against weakpoints. Good for interrupting mobile demons like the imp."

- Doom Eternal dossier protip

Tactical analysis
The heavy cannon is a reliable weapon at medium to long range, requiring no more than two body shots to kill most fodder monsters. It is not as effective against stronger foes on its own, but can be used to supplement other weapons at long range.

The Precision Bolt greatly increases the weapon's accuracy and also deals extra damage to weak spots, enabling one to destroy, for example, the arachnotron's cannon or the revenant's rocket launchers. Using the precision bolt is also the best mod to use to kill Maykr drones as they drop a considerable amount of resources once killed with a headshot. By contrast, micro missiles are best used to deal area-of-effect damage without risking the self-inflicted injury that would come with using the rocket launcher in close quarters.

Modifications

 * Precision Bolt
 * Adds a scope to the heavy cannon, greatly increasing its effective range when aiming down the sight. The heavy cannon fires slower and uses six bullets per shot when using the scope, but deals more damage and receives a bonus when targeting weak points. Its shots can also pierce weaker monsters.


 * Micro Missiles
 * The micro missile mod provides a dramatic temporary power increase, allowing the firing of up to six explosive missiles which detonate on impact. The missiles have minor homing abilities. Reloading is necessary in between salvos.

Precision Bolt

 * Mobility
 * Precision Bolt movement speed is increased by 15%


 * Fast Loader
 * Precision Bolt reload speed increased by 20%


 * Headshot Blast
 * A headshot kill will set off a powerful, secondary blast that deals damage to nearby demons
 * Mod is unlocked by performing 75 headshots while scoped in with the Precision Bolt mod

Micro Missiles

 * Quick Recharger
 * Micro Missile reload time is decreased by 35%


 * Instant Loader
 * Micro Missile load time is decreased by 75%


 * Primary Charger
 * Kills with the Heavy Cannon will boost Micro Missiles damage by 30% for 5 seconds


 * Bottomless Missiles
 * Fire Micro Missiles indefinitely without requiring a reload
 * Mod is unlocked by hitting at least three enemies in a single Micro Missile volley 15 times

Lore
Most of the heavy cannon's components are forged from an alloy called Tungstronium, which allows the weapon to withstand the stresses imparted by its exploding dart ammunition but also contributes to its significant bulk. Although the added weight is a common complaint among users, it mitigates swaying and tremors making the heavy cannon an ideal sniper rifle.

QuakeCon 2018
The heavy cannon is one of the two main weapons that the Doom Slayer starts with during a modified version of the Super Gore Nest level (in which it is accurate to begin the level with the heavy cannon, as it is obtained much earlier), the other being the super shotgun. It is noted that throughout the gameplay reveal, the micro missile mod has yet to be seen at that time, hence, only the Precision Bolt mod is used all throughout.