It takes a strong back to carry more than one or two of these weapons, but any weapon that benefits from the Heavy Gunner perk qualifies as a heavy gun.
Broadsider
Standard Model: Broadsider
Damage: 108 (ballistic)
Ammo: Cannonball
Fire Rate: 2
Range: 203
Accuracy: 63
Weight: 38.1
Value: 245
As a handheld cannon, the Broadsider is about as simple as heavy guns get. Each shot launches a cannonball toward your target, causing impressive ballistic damage on impact. It takes quite a while to reload between shots, but the weapon can be modified to improve its rate of fire.
The Broadsider is received as part of Side Quest: Last Voyage of the U.S.S. Constitution.
Attached Mods
Standard barrel
Standard grip
Standard shot canister
Cryolator
Standard Model: Cryolator
Damage: 20 (energy)
Ammo: Cryo Cell
Fire Rate: 90
Range: 71
Accuracy: 66
Weight: 13.2
Value: 302
The Cryolator sprays a freezing mist that slows targets while dealing energy damage, and sustained blasts can temporarily freeze enemies, causing them to take additional damage from incoming attacks. Due to its limited ammo capacity, however, the Cryolator requires frequent reloads. This unique weapon does accommodate a Crystallizing Barrel mod, which allows it to fire cryogenic capsules for increased range and bonus ballistic damage.
The Cryolator is located in Vault 111.
Attached Mods
Standard barrel
Standard stock
Standard sights
Fat Man
Standard Model: Fat Man
Damage: 468 (ballistic)
Ammo: Mini Nuke
Fire Rate: 1
Range: 117
Accuracy: 63
Weight: 30.77
Value: 512
Used to launch devastating Mini Nukes, the Fat Man boasts unrivaled per-shot damage. Once launched, a Mini Nuke quickly loses altitude. Aim slightly above your target or use V.A.T.S. to help ensure an accurate shot. Either way, make sure you’re a safe distance away from your target—a Mini Nuke has a sizable blast radius.
Attached Mods
Standard Launcher
Experimental MIRV
Damage:18 (ballistic)
Ammo:Mini Nuke
Fire Rate: 1
Range: 117
Accuracy: 63
Weight: 36
Value: 650
What do you do when a single Mini Nuke isn’t enough to get the job done? You convert your Fat Man into an experimental MIRV! Each shot launches a cluster of Mini Nukes. Launch into the air to send Mini Nukes showering on your enemies, or aim for your target for a more contained explosion. This heavy gun packs more than enough power to make short work of the most formidable foes.
Attached Mods
MIRV Launcher
Flamer
Standard Model: Flamer
Damage: 12 (energy damage)
Ammo: Flamer Fuel
Fire Rate: 90
Range: 47
Accuracy: 53
Weight: 16.1
Value: 137
This classic heavy gun spews a stream of fire, dealing energy damage to any targets caught in the flame. It has a fairly short range, however, so it’s best used against melee attackers and unarmed enemies.
Attached Mods
Standard tank
Standard barrel
Standard propellant tank
Standard nozzle
Gatling Laser
Standard Model: Gatling Laser
Damage: 14 (energy)
Ammo: Fusion Core
Fire Rate: 272
Range: 203
Accuracy: 48
Weight: 19.3
Value: 804
Gatling lasers are powerful, rapid-fire energy weapons, capable of dealing serious damage in a short amount of time. A standard Gatling laser fires comparatively weak beams at a very high rate, but these heavy guns can be modified for increased per-shot power at a slower rate of fire.
Gatling lasers are often carried by particularly powerful Brotherhood of Steel soldiers. Like Power Armor, these weapons are powered by Fusion Cores, so it can be difficult to maintain a good supply of ammunition.
Attached Mods
Gatling laser receiver
Standard barrel
Standard sights
No muzzle
Junk Jet
Standard Model: Junk Jet
Damage: 40 (ballistic)
Fire Rate: 20
Range: 119
Accuracy: 75
Weight: 29.9
Value: 285
The Junk Jet turns your unwanted items into powerful projectiles. Just fill this weapon with superfluous junk items and fire away. The standard Junk Jet deals ballistic damage, but it can be modified to add bonus energy damage to each shot.
The Junk Jet is located in ArcJet Systems, and it can be collected during or after Brotherhood of Steel Quest: Call to Arms.
Attached Mods
Short barrel
Standard stock
Standard sights
No muzzle
Minigun
Standard Model: Minigun
Damage: 8 (ballistic)
Ammo: 5 mm
Fire Rate: 272
Range: 131
Accuracy: 35
Weight: 27.4
Value: 382
The Minigun combines low per-shot damage with an impressive rate of fire, resulting in a very effective ballistic weapon. Its high ammo capacity allows for sustained fire, and with the available barrel modifications you can improve its fire rate, accuracy, and overall damage.
Attached Mods
Standard barrel
Standard sights
No muzzle
Missile Launcher
Standard Model: Missile Launcher
Damage: 150 (ballistic)
Ammo: Missile
Fire Rate: 2
Range: 203
Accuracy: 65
Weight: 21
Value: 314
The missile launcher is less powerful than the Fat Man but has a better range and its ammunition is easier to come by. It can be customized to lock on to targets, improve damage, minimize reloads, and more. An appropriately modified missile launcher is generally your best defense against hostile Vertibirds.
Attached Mods
Standard barrel
Standard sights
No muzzle
Plasma Gun (Thrower)
Standard Model: Plasma Thrower
Damage: 12 (ballistic), 12 (energy)
Ammo: Plasma cartridge
Fire Rate: 90
Range: 35
Accuracy: 68
Weight: 4.2
Value: 146
The plasma gun can be used to make powerful pistols and rifles, but it also serves as a solid heavy gun. With an attached Flame Barrel mod, this weapon fires a stream of searing plasma. The combination of ballistic damage and energy damage ensures that it’s effective against most enemies, and its comparatively low weight makes it an excellent choice as a secondary heavy gun.
Attached Mods
Standard capacitor
Flamer barrel
Standard grip
Standard sights