Machine gun

The machine gun, also known as the MG-88 Enforcer, is a versatile weapon introduced in Doom 3. It has a big magazine size, high rate of fire, and great accuracy. It is useful against most demons up to the Cacodemon and especially useful against the Lost Soul. Its default key is 4. The machine gun uses ammo from machine gun magazines. It has very fast rate of fire, but less power in one bullet than the pistol. It should be used to mow down hordes of lesser demons or zombies. It can also be used for long-range work against enemies who are hiding behind cover. Take note that the ammo counter is on the weapon itself and not on the game HUD - similar to BFG 9000, chaingun and plasma gun. In Doom 3: Resurrection of Evil, it is now the main starting weapon in Multiplayer while the pistol acts as the Sidearm.

It is first found in Mars City Underground after unlocking the second storage locker from T. Brooks' computer. If not, it can be found in Mars City off of one of the Z-Secs.

While the pistol, machine gun, and chaingun all fire bullets, they do not use the same caliber and thus do not share the same ammo pool, as in earlier Doom games.

It is probably based on the FN P90 personal defense weapon, with UAC design. Note, however, that no iron sights, optical sights or electronic sights are present on the MG-88; were it to be reproduced in real life, the weapon cannot be accurately aimed at longer ranges, making it next to useless as anything other than a hip-fired "spray and pray" weapon. It should be noted that firing without using sights in reality is regarded as useless and inadvisable unless at extremely close quarters.

Tactical use
Machine guns are good in medium to short range situations against lightly armored foes. Zombies make the best targets being slow and weak. Trites are also best picked off with the machine gun, as well as Cherubs and Lost Souls.

The machine gun is most effective against Z-Secs (aside from the ones with Riot Shields) as it takes down the lightly armored foes quicker than the pistol due to its high rate of fire and is more accurate than the shotgun at medium-to-long range. In a tight spot, machine guns are good versus Maggots and Imps as well. On lower difficulties, a player with a good aim can easily deal with a Demon.

The weapon's rate of fire has two drawbacks. The first is that rapid fire causes the weapon's recoil to disrupt the player's aim. The second is that the weapon burns through its magazine quickly. When using the machine gun, it's recommended that you are near cover in case you need to reload during the middle of a firefight. Generally, the weapon is an ideal firearm to have at the ready whenever the player enters a new area but does not know what is waiting there.

This weapon can be first picked up in the Underground. If not obtained there, it can be picked up from a dead Z-Sec in Mars City.

In Classic Doom
A machine gun was originally going to be used in Classic Doom. First-person sprites for it exist in both the 0.4 and 0.5 alphas. The weapon's appearance, much like the rifle, changed between the versions. It was presumably replaced by the chaingun.