MA5B assault rifle

The MA5B Individual Combat Weapon System was an assault rifle used by the UNSC Marine Corps and Navy throughout most of the Human-Covenant War. It was easily one of the most recognizable and pervasive infantry weapons fielded by the UNSC during conflict with the. The MA5B perfected and refined the defining features of the rifles introduced by the ubiquitous, such as the electronic ammunition counter and enhanced electronics suite, while also introducing new features like internal attachments and a larger, redesigned magazine. The massive success of the MA5B would lead to an even more successful weapon which debuted at the very end of the war: the MA5C.

Developement
The MA5B ICWS was commissioned by the UNSC just following the in the, which included the uprising on  in 2492 and the  in 2494. Fearing the worst, the UNSC commissioned a number of weapons in order to update its aging arsenal in preparation for the possibility of civil war.

Misriah Armory and a handful of other weapons designers quickly churned out a number of prototype weapons. While most were quickly turned down, there were several that showed promise, including XM392A2, The XM55, the XMA25A1, the XM90A and the XSRS-99 Series 2. The XMA25A1 proved to be a hit amongst the marines who demonstrated the weapons, but most stated they disliked the designation, which they found to be a mouthful. Misriah Armory responded to this by making the decision to redesignate the rifle the XMA5B, and similarly renamed the XM55 the as well.

The newly christened XMA5B was a heavily revamped version of Misriah's MA5 assault rifle that was adopted by the in 2437. The weapon built further upon the principles that led to the success of the original MA5; ruggedness, versatility, and vicious medium-to-close-range firepower. Thanks to remarkably few setbacks in the rest of the development process, the finalized model of the XMA5B, now the MA5B Individual Combat Weapon System, was finished in record time, and in 2506 the UNSC Marine Corps adopted the MA5B to replace the MA5 as their primary service rifle, with the UNSC Navy following suit in 2514. However, the and  opted to keep fielding the original MA5 (known as the MA37 by the Army), since it was cheaper, still highly effective, and still receiving ongoing manufacturer support from Misriah.

Design Details
The MA5B was a marked improvement over the original MA5 rifle. The operation of the weapon was almost the same as the original MA5, though the reloading and locking process was made faster and more efficient, allowing for increased rate of fire, and the barrel was given very slight sound-suppressing properties to decrease the volume of the sound made when firing the weapon. The latter change was made to lessen the chances of the weapon's operator suffering hearing loss, which was a relatively common issue with the original MA5, as it was exceptionally loud. The end of the barrel was also threaded for attaching (which were not shipped with the MA5B like they had been with the original MA5 rifle) or  to the weapon.

Unfortunately, Misriah overlooked one major issue with the MA5: suboptimal barrel twist. The barrel twist was 1 in 5.75, which was a poor choice for the weapon's caliber, as most other rifles chambered for a 7.62x51mm cartridge used at least a 1 in 10 twist. This resulted in the weapon being highly inaccurate at longer ranges.

The MA5B also featured a lightweight weather-resistant casing made from a stamped aluminum-based alloy and a heavy-duty plastic polymer. Another new feature was an internal rail attachment system; the heavy-duty below the barrel could be removed and  such as, , or   could be affixed to the inside of the weapon, and could be done so with little difficulty and even in the field thanks to a small field-stripping toolkit located within the front end of the barrel shroud.

The electronics suite on the MA5B, unlike most UNSC weapons, included much more than just a wireless uplink that uploaded a into the user's field of vision vision via  or into any visual displays that the operator may have been equipped with, but it also included an integrated ammunition counter, digital clock (which synchronized with the operator's neural interface upon activation of the weapon's electronics to ensure accuracy, and could be set to synchronize with other equipment the operator may have possessed if they did not have a neural interface or if their neural interface was not properly functioning), and a rudimentary digital compass. The weapon also featured retractable intended for use by non-UNSC users, who often lacked a device to upload a reticle into.

Ammunition
The MA5B was chambered for the UNSC's standard rifle cartridge, the M118 7.62x51mm AP-FMJ round. The 7.62x51mm round had historically been considered by most to be a full-power rifle cartridge, but advances in antiballistic armor eventually made lower-caliber rifle cartridges like the 5.56x45mm round obsolete. This caused the 7.62x51mm round to be downgraded into a gray area somewhere between a low-power and a full-power rifle cartridge. Therefore, based on their performance, weapons like the MA5B could be considered assault rifles while weapons like the could be considered battle rifles, despite being chambered in the same caliber.

Aside from standard armor-piercing rounds, the MA5B could also fire a number of specialized cartridges. One such cartridge was the, known more formally as the M149 .308 Soft-Jacket Fragmentation cartridge. The shredder round consisted of a bullet composed of numerous interlocking pieces linked to a weighted core by thin wire, which was coated in a soft metal shell. When fired into a material of sufficient density, such as flesh, the soft metal shell would tear open, the bullet would break apart, and the weighted core would penetrate the material and drag a number of sharp, irregularly-shaped metal bits in with it. Shredder rounds reduced the chances overpenetration while maximizing cavitation and stopping power, but they were also only effective against lightly-armored personnel. was able to use shredder rounds to great effect against a horde of frenzied during the  in 2535.

Aside from shredder rounds, the MA5B was capable of firing a number of firing a number of flechette rounds, nonlethal cartridges, and other non-standard ammunition types.

Advantages
The MA5B was an devastatingly effective weapon against the. Its brutal stopping power and ferocious rate of fire could tear through moderately-armored targets with ease, and its 60-round magazine meant that numerous enemies could be neutralized off of a single reload.

Against Covenant troops, the MA5B was less effective, but it still performed quite admirably. Less protected foes like Grunts or were still easily shredded by the hail of bullets that the MA5B was capable of unleashing, however, Covenant troops equipped with  such as  could often shake off fire taken from an MA5B at range without trouble, thus weapons like the M392 DMR or the  were considered more ideal for engaging shielded enemies due to their superior accuracy. But the MA5B was found to be surprisingly accurate when fired in short, controlled bursts, and quickly developed a simple method to effectively engage Elites with the MA5B at most ranges: "pulsing" the trigger to release quick, accurate bursts of fire while drawing in closer to the alien, then opening up with fully automatic fire once up close, as an Elite's energy shielding usually could not withstand more than a few short moments of continuous close-range fire from the MA5B.

The MA5B's relatively poor performance against shielded targets while at range would continue to be an issue throughout the Human-Covenant War, but the SPARTANs' method of dealing with the issue became adopted as the standard tactic for engaging shielded enemies with the MA5B, and additional tactics for engaging shielded foes effectively with the weapon were developed over time as well.

In situations in which accuracy was secondary to rate of fire, the MA5B was second to none amongst the UNSCDF's small arms arsenal. Even the paled in comparison to the MA5B, as the M7's higher rate of fire was overshadowed by the MA5B's more manageable recoil and greater stopping power.

The MA5B was also one of the most durable infantry weapons fielded by the UNSCDF. The MA5B could be submerged in mud, then taken out and fired without issues and without having to clean the weapon, similar to the infamous AK-47 of the 20th century. The MA5B fared far better in harsh conditions than the much more tempermental M392 DMR or BR55, leading to it being heavily favored by Marine Special Forces, including and the Hostile Environment & Hazardous Operations Group. The SPARTAN-II supersoldiers also often used the MA5B as their weapon of choice, as they trained heavily with the weapon, and most of them were issued one of their own.

Disadvantages
As mentioned above, the MA5B's poor accuracy at range was its primary drawback. Even with a number of methods of compensating for this being available, using the MA5B at range still often resulted in a considerable quantity of ammunition being wasted. Due to this, Marines still often only used the MA5B at longer ranges as a last resort.

In addition to poor accuracy, the MA5B was also unable to share magazines with the original MA5, the M392 DMR, or the MA5C, despite all of these weapons being chambered for the same cartridge as the MA5B. Not only was this inconvenient for troops on the battlefield, but it was also a nightmare for UNSC logistics. Shipments of box magazines for these weapons were mixed up all too frequently.

As time went on and the UNSC's MA5B arsenal began to age, another design flaw reared its ugly head. When the MA5B was fully loaded, the large quantity of rounds packed into the weapon's box magazine put a considerable amount of stress on the internal magazine spring. If magazines were left loaded for long periods of time, the spring would begin to plastically deform, meaning that when the rounds were removed from the magazine the spring would no longer deform elastically back into its original uncompressed state. This meant that the internal magazine spring was no longer able to push every round into the MA5B's receiver, resulting in failure-to-feed malfunctions. Though frustrating, the problem was relatively easily corrected by replacing the internal magazine spring or by simply using an entirely different magazine altogether. Still, later MA5 models reverted back to 32-round magazines in order to avoid the issue altogether.

MA2B Individual Combat Weapon System
Shorfly after the adoption of MA5B, the Marine Corps began modifying a handful of the weapons into a lighter form more suited for use by special forces teams. The result of their efforts was the MA2B Individual Combat Weapon System, a stripped-down and heavily-modified MA5B. The entire barrel shroud was removed, and its place a set of non-retractable iron sights and a carrying handle were welded to the weapon. The handle included a picatinny rail for mounting optical attachments. The underbarrel atachment system was also replaced with a plastic handgrip riveted to the underside of the weapon, and much of the external casing was removed. A portion of the barrel was sawn off as well, and a flash suppressor was attached to the end. Finally, the MA2B was re-chambered for a .390 caliber cartridge, giving it increased stopping power, but the shortened barrel length reduced the accuracy considerably, largely limiting the MA2B to close-range engagements only.

Despite widespread popularity amongst the, the MA2B was a crude and imprecise weapon, and was thus quickly phased out following the adoption of the vastly superior MA5K.

MA5K Universale Kommando Karabiner
In the mid 2530s, commissioned a replacement for the MA2B. Misriah Armory subsidiary Heckler & Koch set to work creating an improved carbine variation of the MA5B, scrapping the MA2B's design entirely. The result of their efforts was the MA5K Universale Kommando Karabiner, which was paradoxially both more compact and more accurate than the MA2B. The MA5K was a massive hit amongst UNSC special warfare units, and the MA2B was completely phased out in favor of the MA5K by 2543.

UNSC Remarks
"Sometimes the rookies like to say that the MA5B is too weak, but everyone just laughs at 'em. Sure, the DMR'll cut up a Split-Lip or from a ways, but try keepin' yer wits about ya well enough to stop one of those foxtrots with it when they're breathin' right down yer goddamn throat! That's somethin' I've only seen SPARTANs do, and, well, not many of us are goddamn walkin' tanks, now are we? The MA5B'll send anything short of a down in a bloody heap in a couple of seconds."

- An anonymous UNSC Marine Corps NCO.

"There are some marines who you just never see without their assault rifles. If you didn't know any better, you'd think that they sleep with 'em, if you know what I mean, heh heh."

- An anonymous UNSC marine.

"When those damn Covie foxtrots attacked in '25 or '26, some guys were nervous about fighting them. Not me, though. I knew that not even the Devil himself could stand up against me and my assault rifle."

- An anonymous ODST.

"If you're using the MA5B up close, keep your mouth closed. That damn gun just chews shit up like you would not believe. Blood, guts, skin, fat, muscle, and bone; it all comes flying out at you. It's also a good idea to be wearing eye protection; a buddy of mine lost an eye when a bone fragment flew up and hit the poor bastard right square in the face."

- An anonymous UNSC marine.

"The MA5B? That thing ain't a rifle... It's a goddamn power saw."

- An anonymous UNSC marine.

"The MA5B is a damn good gun up close, but at range the accuracy is just shit. My platoon lost two squads to a packing a 'cause nobody could land a hit on the mike-foxtrot before it blasted their goddamn skulls in. Can you believe that shit?"

- An anonymous UNSC marine.