BR55 battle rifle

The 9.5x40mm Service Rifle, BR55, more commonly referred to as the BR55 battle rifle or simply as the BR55, was a high-caliber, selective-fire battle rifle which saw use in the UNSCDF as a special-issue infantry rifle throughout much of the Human-Covenant War. Hastily developed as a countermeasure to a threat that would never truly emerge, the BR55 seemed doomed to failure until the arrival of the in human space saw UNSC forces pitted against foes equipped with regenerating, against which the UNSC's standard  performed less than effectively. The unexpected success of the BR55 rifle would lead to the introduction of an improved version of the weapon, the, following the conclusion of humanity's cataclysmic war with the Covenant.

Development & Service History
The BR55 battle rifle began life as the XM55, an experimental assault rifle platform chambered in 7.62x51mm. The firearm was pitted against multiple other designs in a bid to replace the aging MA5 rifle, but would ultimately be cast aside in favor of the more resilient XMA25A1, a derivative of the tried and true MA5 design that would go on to become the MA5B ICWS. Still, the XM55's exceptional stability and recoil control were duly noted.

However, in 2516 Insurrectionist rebels on the colony of created a chemical cocktail out of a variety of illegal street drugs, stolen hospital drugs, and various over-the-counter medicines. Nicknamed '', the chemical was a form of synthetic adrenaline laced with a fast-acting coagulant. Humans injected with the substance entered a berserker-like state of intense rage, and became extremely resistant to pain and injury, as well as incredibly strong. Nearly one hundred insurgent soldiers would inject themselves with these rumbledrugs and charge blindly at UNSC patrols on the streets of the planetary capital. This was terrifyingly effective, with the rebel soldiers achieving an average kill rate of nearly three-to-one, as they were able to withstand countless hits from an MA5 rifle or.

Fearful that rebels throughout the would begin to create their own rumbledrugs to use in a similar manner, the UNSC put Misriah Armory to work developing a specialized cartridge that possessed tremendous firepower in order to allow UNSC soldiers to incapacitate rumbledrug users before they could inflict much damage.

The result was the M634 Experimental High-Powered Semi-Armor-Piercing round, a 9.5x40mm cartridge capable of inflicting devastating bodily harm on even moderately armored infantry. However, the cartridge generated extremely high amounts of recoil when fired, limiting accuracy severely. In order to account for this, Misriah repurposed the XM55 design to fire this new cartridge. The result was the, a high-powered battle rifle with prodigious stopping power and accuracy far beyond that of the MA5 or MA5B.

Unfortunately, in 2520, just as the development process was wrapping up, the UNSC abruptly withdrew their funding. The UNSC's fears of rumbledrugs seeing widespread use by rebel forces had proven unsubstantiated, and rebels had not been recorded to have been using them at any point following the incident on Green Hills. Furious and unwilling to allow their money and effort to go to waste after four years of development, Misriah officials insisted that the UNSC continue funding the project. Reluctantly, the UNSC eventually agreed.

By 2522, the first XBR55 rifles were arriving in the hands of UNSC forces in the Outer Colonies. Reception of the weapon was mixed; although its performance was undeniably exceptional, it did not particularly excel in any area which the MA5 or M392 DMR did not already perform well in. It lacked the rate of fire and durability of the MA5 and its accuracy and range were both somewhat inferior to that of the M392 DMR. The only area in which it outclassed both weapons was in stopping power, and the 7.62x51mm cartridge used by both the MA5 and M392 possessed stopping power that was already plenty sufficient. Additionally, the weapon was highly intolerant of the rough conditions found on many Outer Colonies, and required constant maintenance in order to remain functional.

But in 2525, the alien empire known as the Covenant attacked the colony of. Many of the Covenant's infantry, particularly the so-called, were far more durable than human soldiers. It was against troops like these that the XBR55 truly shined, able to take down such resilient troops quickly and reliably from a safe distance. And once the energy-shielded started to become a common sight by 2526, it was clear that the XBR55 would be an invaluable asset to the UNSC in the budding conflict between humanity and this terrifying alien foe.

By 2528, Misriah had tweaked and finalized the design of the rifle (most notably reducing its magazine capacity from sixty rounds to thirty-six rounds for weight reasons), and the UNSC official adopted the weapon into their arsenal, naming it the 9.5x40mm Service Rifle, BR55.

Although rebel forces would again use rumbledrugs on the colonies of and  in a desperate attempt to defend themselves against, had the Covenant never attacked this would've been far too little far too late for the UNSC to justify adding the BR55 into its arsenal. The fact that it ever was adopted by the UNSC is mostly the result of pure coincindence. While the MA5 remained the backbone of the UNSC arsenal throughout the BR55's service life, the BR55 was nevertheless an extremely common sight on the battlefields of the Human-Covenant War, particularly in the. In 2548, a heavy-barrel marksman variant entered service in the UNSC, replacing the M392 DMR as the primary squad-level marksman weapon for all branches of the UNSC (with the exception of the ) for the remainder of the war. An updated model of the BR55, the BR85, began introduction in small numbers during the final months of 2552, and the BR55 would finally be phased out of service entirely in favor of this newer model by 2555, after roughly two decades of service.

Design Details
Designed to put extreme stopping power in the hands of the average infantryman, the BR55 was a gas-operated, general-purpose infantry rifle chambered in 9.5x40mm. By twenty-sixth century standards, this unusually large caliber qualified the BR55 as a battle rifle, a classification of firearm not commonly used as a standard-issue, workhorse infantry weapon since the mid-twentieth century.

However, prior to the Covenant invasion of Harvest, the 9.5x40mm M634 X-HP-SAP cartridge was considered overkill, as it provided far more stopping power than a normal soldier could expect to need. To make matters worse, the recoil of the 9.5x40mm cartidge, while somewhat negated by the recoil-dampening design of the weapon, was still much greater than that of the MA5, and thus while the BR55 technically boasted a greater rate of fire than the MA5, its recoil would force its operator to cease firing momentarily and re-sight their targets in order to ensure that their shots remained on target. This ultimately meant that the BR55 was unable to land shots on man-sized targets at close to medium range as quickly or effectively as an MA5 rifle was. To make matters even worse, the BR55 was notoriously intolerant of the muddy or dusty conditions that were common on many Outer Colony worlds, further limiting its appeal in the eyes of UNSC forces deployed against Insurrectionist insurgents.

But the BR55 would prove itself as an invaluable component in the UNSC's arsenal when the Covenant attacked. Unlike the MA5, the BR55's high-energy rounds were capable of quickly and effectively breaking Covenant energy shields, and its greater effective range allowed UNSC Marines to pick off Covenant infantry from afar, where they could more easily react to incoming Covenant plasma fire.

The BR55's final production model would be optimized for three-round-burst firing, as UNSC troops favored this fire mode as it provided the best balance in terms of firing rate and recoil control. While the BR55 and its successors were all select-fire weapons boasting automatic, semi-automatic, and burst fire modes, it was the burst mode that would become closely associated with the BR55 design. Additionally, BR55 rifles manufactured after 2532 featured a rate reducer which would engage when the weapon was set to fully automatic, in order to make the recoil easier to control when firing the weapon in this mode. In spite of this improvement, burst firing would remain the most heavily favored fire mode.

BR55 Heavy-Barrel Service Rifle

 * Main article: 

By 2545, the BR55 design had thoroughly proven itself in battle. Using data collected on the weapon's performance over the past decade, Misriah honed the BR55's ballistics to a razor's edge, developing a modification of the BR55 with range and accuracy superior to that of the M392 DMR. Known as the BR55 Heavy-Barrel or BR55HB, this new version of the weapon was significantly larger and heavier, featuring a longer, heavier barrel intended to increase accuracy and reduce harmonic vibrations generated when firing the weapon. The gas block was moved further down the barrel as well, in order to decrease dwell time and reduce pressure on the gas port.

Prototypes for the weapon were in the hands of UNSC marksmen by the later months of 2546, and the weapon was well received. All branches of the UNSC would phase out the M392 DMR in favor of the BR55HB in 2548, with the exception of the Army, who believed that the increase in accuracy and range did not make up for the considerable increase in weight and size over the M392, nor for the BR55HB's noticeably higher malfunction rate.

During the later days of the Battle of in 2552, a shortage of functional MA5 or standard BR55 rifles and a surplus of BR55HB rifles would lead to the latter weapon seeing its way into the hands of normal UNSC troops as an improvised all-purpose weapon, despite its intended purpose as a marksman rifle. The BR55HB performed surprisingly well for this purpose, and for this reason the BR85, the successor of the standard BR55, would be updated to feature a heavy-barrel design, albeit in a much lighter and more compact overall frame.

S-55 Precision Rifle
The S-55 Precision Rifle was a modification of the BR55HB intended for the civilian market. Featuring semi-automatic fire exclusively as well as a number of other alterations in order to make the weapon conform with civilian firearm laws, the S-55 was fine-tuned for competition target shooting, although it was still relatively popular for personal and home defense purposes.

Notably, retired UNSC Marine Corps Sergeant Major Ingrid H. Schultz won the 2550 Intercolonial Shooting Tournament using a customized S-55 rifle.

UNSC Remarks
"I wonder who the Romeo-Echo-Mike-Foxtrot was who decided we needed a rifle with half the firing rate of the MA5 and twice the stopping power. Last I checked, innies are humans, not elephants."

- An anonymous UNSC Marine commenting on the questionable usefulness of the XBR55 prior to first contact with the Covenant.

"The BR? She's a fussy little bitch, she is. Doesn't really like getting down and dirty much, but she'll blow the head clean off an Elite when you need her to, so long as you treat her well."

- An anonymous UNSC Marine.

"One of my squadmates had his BR jam twice before he'd even emptied half the mag. I was about to bet him that it'd jam again before he'd fired off the whole damned thing, but he didn't live long enough for me to do that."

- An anonymous UNSC Marine.

"The BR55 is probably the only reason I survived Harvest. If I'd been carrying an MA5, well, I don't even want to think about where I'd be."

- An anonymous.

"I'd heard rumors of a fancy new rifle for some time, but I never actually saw the BR55 until '29, when the Covies first hit Roleath. Our MA37s could cut the to ribbons, but if you were more that fifty or sixty meters from a hinge-head, you probably weren't gonna do shit besides make it mad. But those Marines and their BRs, man, I tell you. After seeing them crack an Elite's skull wide open from about one-fifty meters, you wouldn't believe how pissed I was when I found out the Army wouldn't be issuing those BRs out to us."

- An anonymous UNSC Army trooper.