BR55 battle rifle
From Halopedia, the Halo wiki
BR55 Battle Rifle
Rate of Fire : Average Operation : Gas System with cam mechanism for burst fire Fire Mode : 3-round burst Ammunition : 9.5mmx40 (M634 Experimental, High Power, Semi-Armor Piercing) Damage per hit: High Range : Medium to semi-long Accuracy : Very high Magazine Size : 36 rounds Maximum Ammo : 144 rounds (including fully loaded magazine)
Advantages
Designated the BR55 Battle Rifle, it has reasonable power, decent rate of fire, and high accuracy; proving itself to be one of the most versatile weapons in the UNSC arsenal. With a 2x magnification scope, it can be used to deliver three-shot-bursts accurately from medium-to-long range. Firing at any unshielded target's head (besides Hunters) results in an instant kill (see head shot).
In Campaign, the Battle Rifle is useful against just about any infantry units at medium range. In multiplayer, three bursts bring down standard shields, while one headshot (meaning that only one of the three rounds fired needs to connect) results in death if the shields are down.
Disadvantages
At longer ranges, it is necessary to minimize strafing movements when firing to avoid "splintering" the shot grouping too much. Since each "shot" is really a three-round-burst, certain movements can break up your shot's grouping and greatly reduce accuracy. This also affects accuracy when firing from a moving vehicle such as a Warthog (especially when firing at a 90 degree angle from the vehicle's heading).
Influence
The BR55 is largely based on the US Army's XM8 assault rifle prototypes, and also has features resembling Frace's standard issue FAMAS rifles.
Appearences
The Battle Rifle was not featured in the original Halo 1 but was created for Halo 2. It was designed to replace the Pistol from the original game; this was because the developers felt that the pistol was overbalanced for a weapon of such a small size (and just in general, as compared to the other weapons in the game).
The "BR" was originaly designed by Bungie to fire single shots in semi-automatic rates of fire, but the idea was apparently used instead for the Covenant Carbine. Another idea the developers were working on was a three bullet minimum per burst, and holding the trigger resulted in full auto. Zoomed in, the rifle only shot a single bullet. However, these features were ultimately scraped in favor of the more simplistic design that was used in the final version of Halo 2.
The Battle Rifle will be returning in Halo 3. The screenshot above shows that the "new" Battle Rifle has a longer barrel, and it is widely speculated that this is a silencer.
