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 HUD.

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.

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.

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.

This weapon can be first picked up in the Underground. When you're in the security center, continue to access the console to open not only the weapon lockers next to the elevator, but also a supply closet that houses a health center, and a plasma cell.

If you find a machine gun clip (either on the ground or from a Z-Sec) it usualy has only 10 rounds in it so it is recomended that you accumulate ammo or not use it as often

Doom
A machine gun was originally going to be used in Doom, and the marine is shown to have one on the box art and his sprite.