BR55 battle rifle

Summary
The BR55 Battle Rifle is a bullpup UNSC rifle. It fires a larger bullet than an assault rifle, giving more power but also more recoil. Because of the difficult handling when firing fully-automatic, the BR55 is restricted to three-round bursts.

The rifle is a good all-around weapon. Its biggest problem lies in its magazine size combined with the burst fire, giving only 12 shots before reloading.

Advantages
Designated the BR55 Battle Rifle, it has reasonable power, a 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, Brutes, and Drones) results in an instant kill (see head shot). In Campaign, the Battle Rifle is useful against just about any infantry units at medium and, sometimes, long 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. The "BR" is revered by pro's as the Ultimate Weapon. It is very well balanced in power and fire-rate, and is amazingly accurate if wielded by an expert marksman. It's rate of fire, at maximum, is actually pretty high, almost that of a Plasma Rifle, though with more accuracy and higher velocity. It also looks pretty cool :)

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).

Additionally, the burst fire makes it slightly disadvantaged in close-combat positions, though the melee usually takes care of this. Each bullet also acts as a tracer which gives away the shooter's position.

Use on Covenant
Grunt: Either go for an easy headshot, or pepper the Grunt with rounds until it falls.

Jackal: This is a useful tactic. When confronted by a Jackal with it's shield in defence position, fire a well-placed shot in it's hand, and, as it flinches, get in a headshot.

Elite: Level the Rifle at it's head, and keep firing 'till it falls, or fire a full mag into their chest.

Brute: Fire a first shot to take off their helmet, then another to put their lights out. Only available on High Charity.

Hunter: Dodge behind them, and fire as many bursts as possible into their back before they turn around.

Drone: Fire as fast as you can, and take 'em out of the air.

The Battle Rifle is effective against almost every Covenant. Drones are more of a challenge, as are Hunters.

Influence
The BR55 is largely based on the French standard issue FAMAS assault rifle, and also has features resembling the US Army's prototype XM8 rifles.

Appearances
The Battle Rifle was not featured in Halo 1 but was created for Halo 2, though it makes its first in-universe chronological appearance in Halo: First Strike. 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 originally designed by Bungie to fire single shots in semi-automatic rates of fire, but the idea was apparently used for the Covenant Carbine instead.

Another idea the developers were working on, was a three bullet minimum per burst and full auto that resulted from holding the trigger. Zoomed in, the rifle only shot a single bullet. However, these features were ultimately scrapped 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 below shows that the "new" Battle Rifle, or BR55HB SR has a longer barrel, a modified carrying handle, the Scope resembles the modern-day Trijicon ACOG, and there is now a trigger guard over the trigger, a feature lacking in the Halo 2 Battle Rifle

In addition, the new battle rifle is somewhat boxier, and looks almost cobbled together.

Ammo
It is interesting to note the ammo used for the Battle Rifle. It uses a new 9.5mm x 40 Experimental Round. The 7.62mm x 51 round is a moderately large round used on the MA5B and on modern day marksman rifles and machine guns. The 7.62mm already has a history of having too much recoil because of the bullet's size which made it hard to fire fully-automatically in assault rifles. Having a bigger bullet that is almost 2 mm wider would make recoil worse. Due to this theory, it would make sense to say that future technology might have some role in countering these effects. It could be safe to say also that due to the Battle Rifle's bullpup design, it could counter the recoil effects.

However, the 9.5x40mm ammunition used for the BR55 has less powder in each cartridge than the 7.62x51mm rounds used in the MA assault rifles. So despite having a large bullet diameter, the decrease in powder for each round would actually cause less recoil, making it very tolerable. A burst setting on the rifle would also reduce recoil, preventing the user from spraying a target with high-caliber ammunition, possible causing uncomfortable physical effects such as mild bruising and so on.

The size of the ammo would also have a problem fitting in a 36-round magazine of the current Battle Rifle. If an Heckler Koch G3 (which is chambered in 7.62mm x 51) has a standard magazine count of 20 and be the size that it is, it would be hard to see a bullet much thicker than the 7.62mm fit inside of a magazine of the Battle Rifle's size and with a capacity of 36 rounds. Again, this might have something to do with future UNSC weapon technology. This is a continuous pattern with UNSC assault rifles as a similar instance occurred with the MA5B. The MA5B has a magazine of 60 rounds chambered in the 7.62mm x 51 with a rather "small" magazine size, which looks to be smaller than the Battle Rifle's magazine. On Youtube there is a certain video of Halo 3 that shows a Battle Rifle with an M45 Grenade Launcher along with the Spiker, Sniper Rifle, and MA5C.

Full Combat Load Battle Rifle?
On the Level Quarantine Zone (Level) in Halo 2, the player can find a Battle Rifle from a dead UNSC soldier that, when reloaded, has a total of 236 rounds of ammo total. A few players have speculated that this is the "full" combat load for the Battle Rifle, as the player can normally carry only 144 rounds.

Glitches
The Battle Rifle may be used in several glitches. Although they can be used with all weapons, the BXR weapons glitch allows a user to melee, cancel the animation, and then fire, by tapping B (melee), X right afterwards, and then R (the right trigger/gun). This causes an instant kill to a shielded opponent (Elite in campaign or opponent in matchmaking).

Another glitch is the RRX, also known as the double-shot. When you press R (the right trigger)twice without pausing followed by pressing the X button right after the pressing of the second R, instead of firing a three-round burst followed by a pause, it fires six bullets without pausing, simulating automatic fire. After successfully pulling off the glitch, your weapon reloads but without any reloading animation. The drawback with the glitch originally was that once you did the double shot, you were reloading the weapon and therefore could not interrupt it and start firing the weapon again to perform another double shot. However this was solved by tapping the Y button twice to switch your weapon and to quickly switch back to your battle rifle, which interrupted the reloading procedure and you could thus start double-shooting again. It takes four bursts from the battle rifle to the head to kill a target, so successfully tapping RRXYYRRX while accurately firing gave you the ability to kill an opponent quickly, but it is very difficult to master.

There is also the RRYB, an instant kill glitch where you press the right trigger twice, immediately followed by pressing Y (which switched to your other weapon) followed by pressing B (melee) all while running towards your target. It is essentially a BXR but in reverse and you fire two shots instead of one.

Constant fire - This glitch is not easy to perform, but not hard either. The player must not have host connection of the party else it doesn't work. First, fire one bullet of the BR, next throw a grenade straight away, then tap reload twice or three times quickly before resuming to fire, constantly. If it works you should be able to fire all your ammo without reloading. (RLXX(X)RRRR...)

Trivia

 * It's reticule resembles the symbol of the Zodiac Killer.
 * On the side of the Battle Rifle, (opposite side to the bolt) there are three Chinese symbols. I dunno, but one guy told me they said "The Monkey King".
 * The Halo 3 Battle Rifle is called the BR55HB SR. Which the "HB" most likely stands for "Heavy Barrel".

Character Compatibility

 * Elites
 * Spartans
 * Brutes (High Charity level, only on Legendary, though this is very rare.)
 * Drones (have animation but not used)
 * Jackals
 * Flood Combat Form (Human)
 * Flood Combat Form (Elite)