Chaingun

This article is about the original Doom games weapon. For the weapon in Doom 3, see Chaingun (Doom 3).For the weapon in Doom (2016), see Chaingun (Doom 2016).

D229cgun — The player can obtain a chaingun at the start of MAP29: The Living End, in Doom II.

Decamatch chaingun — The chaingun in use in deathmatch mode on Decamatch.

The chaingun (also known as "gatling gun") is a rapid-firing, multi-barrelled automatic weapon. It uses the same ammunition as the pistol, and is fed from the player's shared stock of bullets.

The chaingun is first found in a secret area of E1M2: Nuclear Plant, and again in a secret area of the following level. It then appears in a non-secret area on E1M4: Command Control. In Doom II, it is first found on MAP03.

The chaingun contains 20 rounds of ammunition when picked up (40 on the "I'm Too Young To Die" and "Nightmare!" skill levels). In Doom II, chainguns taken from fallen heavy weapon dudes contain 10 rounds ("I'm Too Young To Die" and "Nightmare!" skill levels) and, unlike pre-existing chainguns, disappear when crushed beneath doors or moving ceilings.

Combat characteristics

The chaingun always fires in pairs of hitscan shots, as long as the player has two bullets or more. Each bullet inflicts 5-15 points of damage. The first two shots in a volley will always be exactly on target, but if the trigger is held down, later shots will suffer from the same dispersal as pistol shots (standard deviation around 2°, to a maximum of ±5.5°).

The chaingun's rapid rate of fire means that a single enemy caught in its hail of bullets will have little or no chance to retaliate. This is effective against most monsters, particularly demons and cacodemons (but not boss monsters, whose pain chance tends to be very low). The weapon is also highly effective at mowing down hordes of zombies or imps. Because its recoil does not affect the first two shots, it is an ideal weapon for sniping, as the player can tap the fire button for accurate two-shot bursts. The chaingun is also good for finishing off monsters that have been weakened by attacks from more powerful weapons.

However, under most circumstances, ammo consumption must be carefully monitored, as the chaingun's relatively high rate of fire can deplete one's ammo quickly, especially since many of the more powerful monsters can take literally dozens of bullets to kill. In particular the player's inventory only allows for a limited supply of bullets compared to other types of ammunition, plus bullets are scarce compared to shotgun shells. For general combat, the slower-firing (but more powerful) shotgun is usually preferred, allowing the player to stockpile bullets for situations where the chaingun's high rate-of-fire is useful.

Notes

BetaChaingun-AspCor — The chaingun in the press release beta.

As with the rocket launcher and BFG9000, the first-person chaingun sprite is slightly too large for the screen, and can only be viewed with a level or resource editor.
The target of chaingun fire often appears to turn and shuffle rapidly in place, due to the continual interruption of its sprite sequences. Doom's instruction manual refers to this motion as "the chaingun cha-cha."
The chaingun first appeared in the Doom press release beta. Its graphic was slightly different, in that the tips of the barrels did not extend past the barrel band.
Wolfenstein 3D, the game id Software released immediately before Doom, included a similar chaingun. However, it was a blue color, and had a significantly higher rate of fire, functioning as the ultimate weapon in-game; the submachine gun was more in-line statwise to the Chaingun.
If the Doom chaingun is associated with real weaponry, it is a Gatling-style weapon with rotating barrels similar to a minigun. An actual chain gun only has a single barrel and uses an electric motor to drive a chain connected to the bolt assembly, moving it back and forth to load, fire, extract, and eject ammo cartridges.
Unlike most real-world gatling-style weapons such as miniguns, the Doom chaingun has a pistol-grip styled handle and trigger group similar to those found on assault rifles or submachine guns, rather than being an infantry-portable minigun seen in the films Predator (1987) and Terminator 2: Judgement Day (1991). As a result of these characteristics, it's implied that the chaingun can be held single-handedly like a pistol by a muscular user (as illustrated by the Heavy Weapon Dude, or by its appearance in the Doom comic) or perhaps held like an assault rifle.
- The weapon's conventional clip-feed, large gray frontal handgrip, and conventional pistol grip imply that it is an assault-rifle type weapon. Due to the fact that conventional ballistic weapons have heat-management issues in the vacuum of space, a rotary-barrel weapon would last significantly longer, which would make it more appealing to space marines than a conventional assault rifle.
The chaingun first-person sprites imply that the weapon has multiple frontal barrels protruding from its final ring; however, the pickup sprite displays a single barrel protruding past the front ring (as depicted in the Doom comic).
As with all firearm hitscan attacks, the average damage inflicted per bullet by the player's weapon is slightly higher than that of monsters using equivalent attacks.
In the Saturn port, the chaingun fires much faster than it normally would.
In the Game Boy Advance port of Doom II, the weapon fires only one shot at a time, and has a somewhat higher overall rate-of-fire. However, the accuracy of the weapon is significantly lower, due to the fact that the dispersal is cone-shaped rather than fan-shaped, and single shots have the same dispersal as automatic fire.
While the chaingun does not have a reload animation, it makes sense in this particular case, as opposed to the other traditional firearms. It is implied to be belt-fed due to its name and functionality, and that fact is corroborated by the Heavy Weapons Dude's appearance in Doom II (the weapon's pickup sprite is somewhat ambivalent in this regard; it has what appears to be a clip inserted into the bottom of the weapon, though this could be a box that holds an ammo belt, or even just a foregrip).

Data

Chaingun data
Weapon number	4
Damage	5-15 per bullet
Included ammo	20 (40 on skill 1 & 5)
Max ammo	200 (400 with backpack)
Ammo type	Bullets
Shot type	Hitscan
Shots per minute	525.0
Sound	DSPISTOL
Appears in	Shareware Doom Registered Doom Ultimate Doom Doom II/Final Doom
Thing type	2002 (decimal), 7D2 (hex)
Radius	20
Sprite	MGUN (before pickup) CHGG (wielded) CHGF (firing) PUFF (impact, miss) BLUD (impact, hit)
Class	Weapon Pickup

CGTapHistogram — *Damage done by one chaingun tap*

Shots needed to kill^1,2	Mean	Standard deviation	Min	Max
Barrel	2.31	0.49	2	4
Zombieman	2.31	0.49	2	4
Shotgun guy	3.23	0.70	2	5
Wolfenstein SS	5.18	0.91	4	8
Imp	6.12	0.95	4	9
Heavy weapon dude	7.12	1.10	5	11
Lost soul	10.00	1.20	8	13
Commander Keen	10.00	1.20	8	13
Demon	14.79	1.48	11	21
Spectre	14.79	1.48	11	21
Romero's head³	24.42	1.46	20	29
Revenant	29.23	1.53	25	33
Cacodemon	39.02	1.93	35	44
Pain elemental	39.02	1.93	35	44
Hell knight	48.60	2.39	42	56
Arachnotron	48.60	2.39	42	56
Mancubus	58.28	2.60	52	64
Arch-vile	68.04	3.09	61	75
Baron of hell	97.06	4.32	87	107
Spiderdemon	290.57	12.48	265	314
Cyberdemon	387.40	16.66	355	415

This table assumes that all calls to P_Random for damage, pain chance, blood splats, and bullet dispersal are consecutive. In real play, this is never the case: counterattacks and AI pathfinding must be handled, and of course the map may contain additional moving monsters and other randomized phenomena (such as flickering lights). Any resulting errors are probably toward the single-bullet average, as they introduce noise into the correlation between the indices of "consecutive" calls.
In the case of continuous fire, the target must be close enough to compensate for the weapon's recoil.
Assumes that direct hits are possible, which does not occur in any stock map.

Demo files

Chaingun "tapping" technique (file info) being demonstrated on MAP07: Dead Simple.

Appearance statistics

The IWADs contain the following numbers of chainguns (excluding those from fallen heavy weapon dudes) per skill level:

Game	1-2	3	4-5
Doom	21	21	21
The Ultimate Doom	29	29	29
Doom II: Hell on Earth	23	23	23
TNT: Evilution	16	17	15
The Plutonia Experiment	11	11	11

Doom 64

In Doom 64, the Chaingun is depicted with longer perforated/vented barrels and a worn blue tone (rather than its Doom counterpart's polished steel appearance). The handle and trigger group is also more similar to those used on real-world minigun-style weapons. Additionally, it has a smaller blue muzzle flash. The pickup sprite has a somewhat rusty appearance as well. When fired at a consistant rate, the screen will jerk up and down rapidly (though this is only a visual effect that does not mess with the gun's fire or aim at all).

Trivia

The weapon's classic first-person sprites are based off of a toy minigun called the Tootsietoy Ol' Painless.
The weapon was originally an assault rifle or submachine gun-type weapon in the Doom alpha, but was redesigned into a slow-firing rotary-barrel gatling gun to give it immediate visual differentiation from other weapons, as well as to give it its own distinct style.