MachineGunX

This mod changes the default machine gun so its more powerful. You will now have 150 bullets per clip, much higher damage, and a cool plasma effect. Also, it's now black instead of a puke green (to quote the author on that )
Just unzip to your default DOOM3 directory so theres a folder named MachineGunX. To load it up, just select it from the mod menu. What this does: Changes the default machine gun so its more powerful. You now have 150 bullets per clip, much high