Machine gun

The MG-88 Enforcer is a weapon in Doom 3. Its default key is 4. The Machine Gun uses ammo from Machine Gun clips. It has very fast rate of fire, but less power 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.

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.

Machine guns are most effective against Z-Sec's (Riot Shield variants excepted) as they take down the lightly armored foes in a few shots (unlike the pistol) at a comfortable range where they are more or less inaccurate (unlike the shotgun). In a tight fix, machine guns are good versus Maggots and Imps as well. ON low difficulty, even a Pinky is no match for a crack shot on the MG-88.

Rate of fire in the machine gun is something to seriously take into account. The accelerated firing rate means a lot of hurt being put down in a relatively short amount of time. This gives the MG-88 a bit of a kick back and can cause aiming difficulties. Also note that the machine gun tears through ammo faster than whatever monster is at the receiving end, and that you should always:

a) Re-load the gun after use. b) Be ready to duck for cover in a firefight and reload.