Chaingun/Doom 3

"The Chain Gun's 0.30 caliber armor piercing round delivers substantial damage, but heavy recoil reduces accuracy."

- PDA Description

The Chain Gun (also known as the UAC Weapons Division Mach 2 Chain Gun) in Doom 3 is the upgraded version of the Machine Gun. It is a heavy multi-barreled firearm that fires larger rounds than those from the Machine Gun.

The Chain Gun first appears in the Martian Buddy storage locker in Administration. It can also be found - along with several ammo belts - in the really dark areas of Alpha Labs Sector 2 through which an NPC named Edwards, will guide the player. The Chain Gun is found by taking a right directly after entering the dark room.

Weapon Schematics
The Doom 3 Chain Gun is very different from it's classic counterpart. The old chaingun was at best, a light rapid fire weapon that was comparable to the Machine Gun, which largely comes from the original chaingun firing the same standard rounds as the pistol. The Doom 3 Chain Gun, on the other hand now utilizes exclusive .30 caliber, armor penetrating rounds, making it much more powerful than the rounds fired from both the Pistol and Machine Gun, but comparatively slower as well.

The Chaingun can hold a total of 60 rounds. Once the rounds are depleted or if the player manually reloads, the weapon's hinged barrel is opened and bullets from the Ammo Belt is inserted inside the barrel, before the player closes it back in. Like the Machine Gun, the Chain Gun has its own buzzer alarm when current ammo belt is reduced to 10 bullets, suggesting the user to reload.

Ammo for the Chain Gun can be found in the form of Ammo Belts. Chaingun ammuntion can also be obtained by picking up Chain Guns (30 rounds) from deceased Chaingun Commandos.

Just like the plasma gun, BFG9000 and newcomer Machine Gun, the ammo counter is located on the weapon itself, instead of the game HUD.

Tactical use
The Chain Gun is the jack of all trades weapon. It possesses reasonable accuracy and rate of fire, making it a reliable weapon to use against any type of enemy, regardless of range. While the Machine Gun is ideal against smaller, lighter targets, the Chain Gun is effective against bigger foes as it fires larger caliber bullets. A single clip is likely to take down larger enemies such as Hell Knights and Mancubi.

Despite its high firepower, the Chain Gun is prone from high recoil. This, in turn, makes the weapon have a slower rate of fire compared to the Machine Gun and Plasma Gun, and also reduces accuracy from continuous fire.

The weapon also suffers from a one second lag caused by it's wind-up time for the barrel. This can be disadvantageous for the player at close range, as it will give enemies enough time to land a first attack, before the Chaingun can start firing. However, it is possible to "pre-spin" the Chain Gun, and keep it revved, reducing the lag to allow it's effectiveness in tight quarters.

The Chain Gun should be reserved for larger enemies such as Demons, Hell Knights, and Mancubi. It is not advisable to use against a swarm of Lost Souls or Cherubs, as this weapon's high recoil and wind up time to fire makes it rather ineffective to take down smaller, more agile enemies.

As Chain Gun ammunition is generally hard to find until the player reaches the Delta Labs (and even then is mostly retrieved from the corpses of Chaingun Commandos), it is recommended to rely more on the Shotgun, Machine Gun, and Plasma Gun until then.

Video Disk - Mach-2 Chain Gun Briefing
Date: 03/20/42
 * Creator: UAC Advanced Weapons
 * Informational video on the Mach-2 Chain Gun
 * In a quest to provide armies with a well balanced set of weapons, the UAC looked to the past when designing and manufacturing the newest line of Mach-2 Chain Guns.
 * The retro style and mechanical sturdiness of the Chain Gun is a must for all hardened combat veterans. Early adapters have nicknamed it 'SAW'. With its armor-piercing, .30 caliber bullets, the Chain Gun is capable of literally cutting opponents in two. Packed with all the punch you need in close combat fighting, the Chain Gun delivers unparalleled reliability and functionality.
 * Always on the forefront of technology, the UAC is making safer worlds through superior firepower.