The BR55 Battle Rifle is a UNSC gas operated projectile weapon. It firest a larger caliber bullet than an assault rifle, giving more power but also more recoil. The BR55 is restricted to three-round bursts of fire.

The rifle is an excellent all-around weapon. Its biggest problem lies in its magazine capacity - allowing only 12 shots before reloading.

NOTE: The closest thing that Halo and Halo 3 players will likely get to the much adored M6D pistol of Halo 1, the go-to weapon in nearly every situation, both in Campaign and Multiplayer. Some bemoaned the lack of a single shot firing mode that was demonstrated in the Earth City video, but it doesn't appear as if that is changing in Halo 3.