When used in a hip firing fashion, the FMG will project a field of high intensity radiation to incinerate it's targets in a wide cone of damage. This weapon's damage and accuracy drops off with range. In this firing mode the weapon will drain it's energy supply over time, but will regenerate soon after the user has stopped firing.
Using the "Iron sights" method of firing the weapon will result in a concentrated incendiary blast at the epicenter of the cursor. The blast does have a splash damage effect which makes it very useful for enemy clusters. When the weapon is fired in this fashion all of its reserve energy will be depleted at once, but after a couple of seconds, will begin recharging normally.
Rather than use a digit like other weapons, ammo (Or energy in this case) is indicated by a circle. When energy is expended, the circle goes narrow in a counterclockwise direction.
There is an unlimited amount of ammo, but the energy needs to recharge after each use.
Considered by most to be the most powerful weapon in the game, it only makes its appearance once during the campaign.