"Thunderhead" Heavy Autocannon

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"Thunderhead" Heavy Autocannon
GearGraphic AutoCannon.png
Equipment Details
Type Heavy Weapon
Used by Gunner
Slot Primary
Hitscan Yes
Availability Unlock
A peculiar but devastating weapon. The slow rate of fire is made up for by heavy damage, delivered with glee by the belt-fed .50-caliber tungsten rounds. The Thunderhead is a somber weapon for the sophisticated executioner, delivering death as inexorably as the passage of time itself.
~ Item Description

About[edit | edit source]

The "Thunderhead" Heavy Autocannon is an unlockable primary weapon for the Gunner. It is an oversized light machine gun with two massive barrels extending outwards which fire in sequence. The weapon is loaded by a huge ammo box.

The Autocannon fires explosive rounds which detonate upon hitting the world or a target. Enemies hit directly by rounds take both the damage of the bullet and the explosive damage at once. The rounds fired start out with a sluggish fire rate, but this can build up over time the longer the trigger is held.

The weapon is incapable of dealing friendly fire to teammates.


Icons Campaign.png Unlocked through an assignment.
Requires Gunner Level 10
Purchased for:
Credit.png 7600 Credits
Croppa 80 Croppa
Magnite 120 Magnite
Initial Stats
Damage 14 kinetic
Area Damage 9 Explosive
Magazine Size 110
Max Ammo 440
Reload Time 5s
Movement Speed While Using 50%
Top Rate of Fire (per second) 5.5
Maximum Damage Radius 0.75m
Radius 1.4m
Minimum Damage 50%
Friendly Fire 0%

Modifications[edit | edit source]

There are five tiers of modifications and each tier has two to three upgrades. Only one modification can be equipped per tier.

"Thunderhead" Heavy Autocannon Modifications
Mod Effect Description Price
Tier 1 Icon Upgrade DamageGeneral.png
Increased Caliber Rounds
+3 Damage The good folk in R&D have been busy. The overall damage of your weapon is increased.
Credit.png 1200 Credits
Bismor 25 Bismor
Icon Upgrade ClipSize.png
High Capacity Magazine
x2 Magazine Size The good thing about clips, magazines, ammo drums, fuel tanks ...you can always get bigger variants.
Credit.png 1200 Credits
Enor Pearl 25 Enor Pearl
Icon Upgrade Ammo.png
Expanded Ammo Bags
+220 Max Ammo You had to give up some sandwich-storage, but your total ammo capacity is increased!
Credit.png 1200 Credits
Croppa 25 Croppa
Tier 2
Level 4
Icon Upgrade Aim.png
Tighter Barrel Alignment
x0.7 Base Spread Improved accuracy
Credit.png 2000 Credits
Croppa 24 Croppa
Enor Pearl 15 Enor Pearl
Icon Upgrade FireRate.png
Improved Gas System
+2 Top Rate of Fire We overclocked your gun. It fires faster. Don't ask. Just enjoy. Also probably don't tell Management, please.
Credit.png 2000 Credits
Jadiz 24 Jadiz
Enor Pearl 15 Enor Pearl
Icon Upgrade FireRate.png
Lighter Barrel Assembly
+50% Rate of Fire Growth Speed Reach the max rate of fire faster
Credit.png 2000 Credits
Enor Pearl 24 Enor Pearl
Bismor 15 Bismor
Tier 3
Level 8
Icon Upgrade FireRate.png
Supercharged Feed Mechanism
+2 Top Rate of Fire We overclocked your gun. It fires faster. Don't ask. Just enjoy. Also probably don't tell Management, please.
Credit.png 2800 Credits
Croppa 50 Croppa
Jadiz 35 Jadiz
Icon Upgrade Area Damage.png
Loaded Rounds
+2 Area Damage Increased splash damage
Credit.png 2000 Credits
Magnite 35 Magnite
Umanite 50 Umanite
Icon Upgrade DamageGeneral.png
High Velocity Rounds
+4 Damage The good folk in R&D have been busy. The overall damage of your weapon is increased.
Credit.png 2800 Credits
Magnite 50 Magnite
Enor Pearl 35 Enor Pearl
Tier 4
Level 12
Icon Upgrade ArmorBreaking.png
Hardened Rounds
+400% Armor Break Bonus We're proud of this one. Armor shredding. Tear through that high-impact plating of those big buggers like butter. What could be finer?
Credit.png 4800 Credits
Jadiz 72 Jadiz
Magnite 48 Magnite
Enor Pearl 50 Enor Pearl
Icon Upgrade Area.png
Shrapnel Rounds
+0.6m Effect Radius Greater splash damage radius
Credit.png 4800 Credits
Jadiz 72 Jadiz
Magnite 50 Magnite
Umanite 48 Umanite
Tier 5
Level 16
Icon Upgrade DamageGeneral.png
Feedback Loop
+10% Damage at Top Rate of Fire Increased damage when at max rate of fire
Credit.png 5600 Credits
Croppa 140 Croppa
Magnite 64 Magnite
Bismor 70 Bismor
Icon Upgrade ScareEnemies.png
Suppressive Fire
+Impact Fear AoE Chance to scare creatures next to a bullet impact
Credit.png 5600 Credits
Magnite 64 Magnite
Umanite 140 Umanite
Bismor 70 Bismor
Icon Upgrade Resistance.png
Damage Resistance At Full RoF
+30% Damage Resistance at Full Rate of Fire Take significantly less damage when at max rate of fire.
Credit.png 5600 Credits
Croppa 64 Croppa
Jadiz 140 Jadiz
Enor Pearl 70 Enor Pearl

Overclocks[edit | edit source]

Overclock calculations happen after modifiers.

"Thunderhead" Heavy Autocannon [Expand/Collapse]
Overclock Effect Description Price
Composite Drums

Frame Overclock Clean.png

Icon Upgrade Ammo.png
Pos.svg +110 Max Ammo

Pos.svg -0.5s Reload Time

Lighter weight materials means you can carry even more ammo!
Credit.png 7850 Credits
Croppa 135 Croppa
Magnite 105 Magnite
Enor Pearl 70 Enor Pearl
Splintering Shells

Frame Overclock Clean.png

Icon Upgrade Area.png
Pos.svg +1 Area Damage

Pos.svg +0.3m Effect Radius

Specially designed shells splinter into smaller pieces increasing the splash damage range.
Credit.png 7300 Credits
Croppa 95 Croppa
Jadiz 125 Jadiz
Magnite 65 Magnite
Carpet Bomber

Frame Overclock Balanced.png

Icon Upgrade Area Damage.png
Pos.svg +3 Area Damage
Pos.svg +0.6m Effect Radius

Neg.svg -7 Damage

A few tweaks here and there and the autocannon can now shoot HE rounds! Direct damage is lower but the increased splash damage and range lets you saturate an area like no other weapon can.
Credit.png 7350 Credits
Croppa 120 Croppa
Magnite 105 Magnite
Umanite 70 Umanite
Combat Mobility

Frame Overclock Balanced.png

Icon Upgrade MovementSpeed.png
Pos.svg +35% Movement Speed While Using
Pos.svg x0.7 Base Spread
Pos.svg x1.5 Rate of Fire scaling
Pos.svg +0.9 Starting Rate of Fire

Neg.svg x0.5 Magazine Size

Fancy custom ammo drums improve weapon balance making it more accurate and easier to handle on the move while the improved feed motor increases the speed with which the max fire rate is reached. All this however comes at the cost of magazine capacity.
Credit.png 7650 Credits
Croppa 70 Croppa
Jadiz 120 Jadiz
Magnite 95 Magnite
Big Bertha

Frame Overclock Unstable.png

Icon Upgrade DamageGeneral.png
Pos.svg +12 Damage
Pos.svg x0.7 Base Spread

Neg.svg x0.5 Magazine Size
Neg.svg -110 Max Ammo
Neg.svg -1.5 Top Rate of Fire

Extensive tweaks give a huge bump in raw damage at the cost of ammo capacity and fire rate.
Credit.png 8400 Credits
Croppa 105 Croppa
Umanite 80 Umanite
Bismor 125 Bismor
Neurotoxin Payload

Frame Overclock Unstable.png

Icon Overclock Neuro.png
Pos.svg +Neurotoxin Payload (50% Chance)
Pos.svg +0.6m Effect Radius

Neg.svg -2 Damage
Neg.svg -5 Area Damage

Channel your inner war criminal by mixing some neurotoxin into the explosive compound. The rounds deal less direct damage and splash damage, but affected bugs move slower and take lots of damage over time.
Credit.png 8100 Credits
Croppa 100 Croppa
Jadiz 75 Jadiz
Magnite 135 Magnite


Stats Breakdown[edit | edit source]

Understanding the Weapon[edit | edit source]

  • Damage is how much damage is dealt upon direct impact of the shot.
  • Area Damage is how much damage is dealt in addition to the direct damage within the damage radius around the impact.
  • Top Rate of Fire is the max rate of how quickly shots can be fired after sustained firing.

Rate of Fire Mechanics[edit | edit source]

  • The Autocannon has two hidden stats regarding rate of fire, which is its Starting Rate of Fire and Rate of Fire Scaling. They play an important role in determining how quickly max rate of fire bonuses are applied, and can be changed depending on which modifications/overclocks are taken.
  • Starting Rate of Fire default is 3.4
    • This determines how quickly shots are initially fired as its rate of fire starts to ramp up.
  • Rate of Fire Scaling default is 0.4
    • This is the coefficient of the exponential function that is used during the rate of fire rampup. The Autocannon's initial rate of fire continues to be scaled until the top rate of fire has been reached, which would then allow max rate of fire bonuses to be applied.
  • Modifications/Overclocks that affect Rate of Fire:
    • Improved Gas System
      • +0.3 Starting Rate of Fire
      • +2 Top Rate of Fire
    • Lighter Barrel Assembly
      • +0.6 Starting Rate of Fire
      • x1.5 Rate of Fire Scaling
    • Supercharged Feed Mechanism
      • +0.3 Starting Rate of Fire
      • +2.0 Top Rate of Fire
    • Big Bertha
      • -1.5 Top Rate of Fire
    • Combat Mobility
      • x1.5 Rate of Fire Scaling
      • +0.9 Starting Rate of Fire
  • Rate of Fire Formula
    • Let S be the Starting Rate of Fire
    • Let C be the Rate of Fire Scaling
    • Let M be the Max Rate of Fire
    • Let t represent the amount of seconds that has elapsed since the Fire button has been held down.
    • The Rate of Fire at any given time, t, can be represented as such:
      • \[R(t) = \min(S*e^{Ct}, M)\]
    • Such that when enough time has elapsed and \[S * e ^{Ct} \ge M\], time is no longer a factor in the Rate of Fire. At this point, the "Max Rate of Fire" Bonuses should kick in.
Rate of Fire Graph[edit | edit source]
Modifications Starting Rate of Fire Rate of Fire Scaling Max Rate of Fire Time to reach Max Rate of Fire
Base 3.4 0.4 5.5 1.2s
Improved Gas System 3.7 0.4 7.5 1.76s
Lighter Barrel Assembly 4 0.6 5.5 0.53s
Supercharged Feed Mechanism 3.7 0.4 7.5 1.76s
IGS + SFM 4 0.4 9.5 2.16s
LBA + SFM 4.3 0.6 7.5 0.92s
Rate of Fire Graph (with Big Bertha)[edit | edit source]
Modifications Starting Rate of Fire Rate of Fire Scaling Max Rate of Fire Time to reach Max Rate of Fire
Base 3.4 0.4 4 0.4s
Improved Gas System 3.7 0.4 6 1.2s
Lighter Barrel Assembly 4 0.6 4 0s
Supercharged Feed Mechanism 3.7 0.4 6 1.2s
IGS + SFM 4 0.4 8 1.73s
LBA + SFM 4.3 0.6 6 0.55s
Rate of Fire Graph (with Combat Mobility)[edit | edit source]
Modifications Starting Rate of Fire Rate of Fire Scaling Max Rate of Fire Time to reach Max Rate of Fire
Base 4.3 0.6 5.5 0.41s
Improved Gas System 4.6 0.6 7.5 0.81s
Lighter Barrel Assembly 4.9 0.9 5.5 0.12s
Supercharged Feed Mechanism 4.6 0.6 7.5 0.81s
IGS + SFM 4.9 0.6 9.5 1.10s
LBA + SFM 5.2 0.9 7.5 0.4s

Unique Modifications[edit | edit source]

Suppressive Fire[edit | edit source]

Icon Upgrade ScareEnemies.png

Suppressive Fire inflicts 50% Fear to all enemies within a 1m radius of where bullets impact either enemies or terrain. Most of the small-to-medium creatures will have Fear inflicted on them by this upgrade. It is important to note that the radius of Suppressive Fire does NOT increase with any mods or Overclocks that affect the Damage Radius.


Unique Overclocks[edit | edit source]

Neurotoxin Payload[edit | edit source]

Frame Overclock Unstable.png

Icon Overclock Neuro.png

Neurotoxin Payload is an Unstable Overclock. It grants all shots a 50% chance to inflict Neurotoxin onto an enemy. When an enemy is affected by Neurotoxin, they will take 12 Poison damage every 0.75 - 1.25 seconds for 10 seconds, as well as having their movement speed reduced by x0.7. Hitting an enemy who is already affected by Neurotoxin with another round which inflicts the debuff will reset its timer.

Mastery[edit | edit source]

Each modification that is purchased advances a mastery bar by one unit.

Mastery unlocks:

  • Three modifications – First Stripe Weapon Paintjob Icon Skin First Stripe.png
  • Seven modifications – Deepcore Weapon Paintjob Icon Skin Deepcore.png
  • All (14) modifications – The Company Special Weapon Paintjob Icon Skin The Company Special.png

Skins[edit | edit source]

Full gallery of skins can be seen at Weapon Skins.

Gallery[edit | edit source]

Trivia[edit | edit source]

  • Mission Control's dialogue upon completing the Weapon License Assignment for the Autocannon reads as follows:
    • "Good work. Management believes you're ready to handle our Heavy Autocannon, the "Thunderhead"... Be mindful not to blow off your own legs with it. This thing has a proper kick to it."
  • In older versions of the game the Powered Minigun also fed from a large ammo drum which needed to be reloaded, on top of its overheating issues. This was changed in Update 11: Dead and Gun to the current system where the Minigun feeds from a single drum and does not reload. It is likely that the Minigun's older reloading system influenced the Autocannon's design when it was added to the game a few months later in Update 19: Guns! Lots of Guns!



This page is up to date for Update 34: Modest Expectations