40px-Terminal.png This article, BR55-M45 Battle Rifle, was written by Spartan 501. Please do not edit this fiction without the writer's permission.
BR55-M45 Battle Rifle
BR55-M45 Battle Rifle
Production information

Bullpup Battle Rifle

Technical specifications

Handheld, Two Handed

  • 90 cm
Damage Per Hit


Magazine Size
  • 36 Rounds
  • 1 Grenade
Maximum Ammunition
  • 180 Rounds
  • 8 Grenades
Fire Mode
  • Three Round Burst
  • Grenade Shot
Ammunition Type
  • M634 9.5x40mm X-HP-SAP (Experimental, High Penetration, Semi-Armor Piercing)
  • M10 HE-GL Grenades

Gas System with Rotating Bolt

Rate of Fire

Average 2.6 Bursts Per Second






Human Covenant War


UNSC, UNSC Special Forces


The BR55-M45 Battle Rifle is a variant of the BR55 Battle Rifle and the BR55HB SR Battle Rifle, with changes including a slightly higher rate of fire, recoil dampeners, and most notably, a mounted grenade launcher.

Physical Description

The BR55-M45 is a bullpup, selective fire, UNSC rifle that fires the 9.5x40mm X-HP-SAP round. It fires from a 36 round magazine which fits flush in the receiver. The receiver is built directly into the underside of the butt of the gun and is located behind the grip (known as a bullpup configuration).

This titanium alloy weapon is gas-operated with a rotating bolt and therefore must be cocked before the first round can be fired. The charging handle used to chamber the round is located on the left side of the weapon and does not move during operation. Once the first round is fired, the gases from that round and those to follow impinge upon a gas piston, which pushes back the bolt carrier, rotating the bolt inside and continuing to chamber rounds until the magazine is empty. Once the magazine is empty, the charging handle can either be pulled back and locked or, it can be fully cycled after a fresh mag has been housed. If it is pulled back and locked, then it must be pushed forward once a fresh magazine is housed to chamber a new round. The magazine release button is located on both sides of the gun with an arrow pointing down towards the housed mag in the stock. The ejection port is located on the right side of the weapon. There is also a fire selector on both sides of the ammo display.

The BR55-M45, not having a rifled barrel, has noticeable changes from the BR55HB SR, similar to the early BR55. The shorter barrel means less accuracy and range, but also ensures easier maneuverability. It is fitted with a Trijicon ACOG-style scope on a modified carrying handle. The safety is also located above the handle of the weapon. The BR55-M45 has a grenade launcher mounted where the grip would be on a standard BR55, and lacks a trigger guard.


The BR55-M45 was developed during the UNSC's effort to create new BR55 variants in late 2552. It was designed specifically with the EABTs and heavy demolition units in mind, and was to be sort of an experiment. For a long time, weapons had not used grenade launchers due to the launchers not being necessary, but in the war against the Covenant, the UNSC was willing to try anything. Some main goals of the weapon were to create a gun that could use a grenade launcher effectively.


  • Shorter, non rifled barrel
  • Grenade launcher firing M10 HE-GL Grenades on grip
  • Recoil Dampeners in butte stock
  • 1x zoom instead of 2x
  • Semi-Auto and three shot burst

Field Usage

The EABTs in the field who have used the BR55-M45 have been generally pleased with the weapons performance, and those who do not have it routinely request it. The EABTs generally use the BR55-M45 once they are inside enemy craft, and in the confined quarters, the grenade launcher is highly deadly. The BR55-M45 has only been fielded to the EABTs and select demolition troops, so it is an excessively rare sight in the UNSC. However, some of these weapons were placed on the Pillar of Autumn in the ships special SPARTAN-II armory, but these were all destroyed.


While a good weapon, the BR55-M45 has definite drawbacks. The primary drawback of the BR55-M45 (though also an advantage in confined spaces) is the non rifled barrel, which makes it less effective over longer ranges. The other primary flaw is not in the weapon itself, but in the development of it; it has only seen limited action and therefore only had limited reportings and remarks.


"The bee are fifty five em forty five (BR55-M45) is a very handy weapon for us EABTs. While we can use our em eh five bee vee sees (MA5B/VC) for combat in vacuum, it is not the greatest help while in a ship, as the mircothrusters that fire in space to stabilize aim don't turn off once your outside of vacuum. Having the em forty five (M45) enables us to fight both inside and outside."

—unnamed EABT

"Whoever thought of attaching an em ten (M10) is an honest-to-god genious. Grenade launchers got phased out in the 24 century because they were useless at that point, but having one on it now, during the fight with the covenant, is great."

—unnamed EABT

"Having a grenade launcher on the bottom of the em forty five (M45) was a definite blessing, like having a mini-rocket launcher on the bottom of your bee are (BR). Nothing during that battle felt better than letting a grenade fly straight into a pile of Bravo Kilos and watching the bones and steaming meat fly."

—excerpt from Jackson Williams' report on the Battle of Artic IV

"The recoil dampening systems in the butte of the gun makes kickback almost non existent. Its so easy to aim, and it feels like your firing something light as air, even when your pumping the trigger on semi, a felling that makes you feel like your an honest to god Sierra-II in that MJOLNIR armor. A word of advice to the brass, implement these elsewhere, in guns like the bee are fifty five eye eh eff eh (BR55IA FA), where recoil kills your aim."

—unnamed EABT

"We demolitions guys were supposed to get exclusive use of the em forty five (M45), then those fox-trotting EABT guys came in and got all of the models. Its a rare sight to see an em forty five (M45) in the hands of a demolitions personnel, but whenever you see EABTs, you seen an em forty five (M45) strapped to their back. Damn them, damn the damned space men!"

—unnamed UNSC demolitions specialist