Fuel Rod Gun
From Halopedia, the Halo wiki
(PC/Mac Multiplayer Only) Rate of fire: Average (2 round per second) Damage per hit: Very high Range: Medium Accuracy: Low-medium Magazine size: 5 rounds per clip Maximum ammo: 30 rounds
Advantages
This explosive gun is a requirement for all Spartans and Elites worth their ass. Unlike their Halo counterparts, they don't have failsafes that make them blow up as soon as you drop them. Fuel rod guns are now magazine-fed, and holds five rounds each. Two to three rounds is enough to blow a Hunter to oblivion. The gun fires fairly fast, and reloads at around the same rate as the rocket launcher. Another similarity is that it has a 2X scope. And just look at all the ammo you can carry! Thirty friggin' rounds, man! The melee attack, while not as strong as a rocket launcher or an energy sword's, is still very lethal.
Disadvantages
The fuel rod gun does not have a tracking device, and the projectiles are slow. It is still capable of killing a user at short range, and ammo will run dry quickly in Legendary. The large size will often obscure your vision, making it harder to see who's there to kill you. Unfortunately, this weapon is not featured in Multiplayer.
Hunter
There are the ones that the Hunters use which shoot out long beams of fuel rod. If only we had some way of taking that gun off a Hunter and use it for ourselves..."sigh"