The MA5B Individual Combat Weapon System (MA5B ICWS or MA5B Assault rifle) is a standard-issue service rifle of the UNSC Marines
The MA5B Assault rifle is an air-cooled, gas-operated, magazine-fed weapon designed for automatic fire. The MA5 series rifle is the workhorse of the UNSC Marine Corps and has been in service for more than fifty years. The MA5B has an attached electronics suite that provides information on rounds remaining in magazine, compass heading, as well as several other "housekeeping" functions. The rifle performs well in a variety of environments especially given the perceived delicacy of the attached electronics suite. The MA5 rifle can be outfitted with a number of modifications including sound suppressors, a grenade launcher or a standard issue flashlight and more “exotic” ammunition types like shredder rounds; however, these modifications are only available by Mission Conditional Requisition (MCR). The MA5B is easily one of the most versatile weapons in the UNSC’s arsenal. Due to this versatility, the MA5B is complimented by many of the UNSC's other weapons as either the primary means to a kill or in a secondary role as the fallback weapon.
The MA5B rifle is a bullpup design and made of titanium alloy and polymer - the rifle is a gas-operated weapon with a rotating-bolt and therefore must be cocked before the first shot can be fired. The charging handle used to chamber the round is situated on the left side of the rifle and moves 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 must both be pulled back and locked or, must be fully cycled after a fresh magazine is inserted to load the next round. The magazine itself is located at the butt of the rifle and the release button is located above the housing with an arrow pointing down toward the housing. The electronics suite is integrated along the top rail guard of the weapon. The MA5B is designed for the toughest of situations, able to be subjected to elements that would otherwise jam and render a weapon inoperable. It has concealed iron sights, although not seen in gameplay and is used by Marines and other personnel with improper equipment to uploading a targeting reticule to the user's HUD or Neural Interface.
The MA5B Assault rifle uses M118 7.62x51mm Armor Piercing, Full Metal Jacket rounds. These rounds are designed to pierce body armor, so the rounds are reasonably large, and are surrounded by a molded jacket of either steel or titanium, which enhances its armor-piercing capabilities. The round might also have a carbide or similar hardened tip, and might also be coated in copper or another metal over the steel, titanium, etc. shell.
However, despite these advanced rounds, the damage done by a single round is very limited, made even worse by the rifle's low accuracy at long ranges. Although performing poorly against Covenant shields, the AP-FMJ round can easily penetrate lightly armored Unggoy and Jackals and kill unshielded Sangheili very quickly. The AP-FMJ round is especially effective against all manners of Flood as they are not well armored. This is somewhat strange, since the AP-FMJ round is traditionally less effective against flesh and unarmored targets due to its tendency to overpenetrate tissue.
The most pressing negative aspect of the MA5B is its inconsistent accuracy. Firing the weapon in short bursts will allow much higher accuracy, as opposed to holding down the trigger. Most of the bullets will stay within the reticule. One round fired may produce a perfect bull's-eye, but the next may fly out of the targeting reticule and slam into the dirt a dozen meters from the same target. This has lead to the belief that the rifle is very incapable of hitting targets greater than close-range; this is untrue. If attacking targets at surprisingly long-ranges, one can effectively wound or kill that target by firing in single shots or bursts. Unfortunately, this lack of consistent accuracy has tarnished the image of the rifle, and the problem has kept the MA5B out of the hands of those who prefer less spontaneous weapons.
The MA5B in both offensive and suppressive situations remains the Marine Corps most reliable weapon. When fired in short bursts, or even single shots, there is a significant increase in accuracy, and the rifle's armor penetrating ability makes it key for handling even the toughest of infantry, having the ability to kill a Sangheili in approximately 45 rounds in close quarters. The rifle is effective at killing light armored infantry at close-to-medium range, and the high rate of fire combined with the high ammunition capacity allows its user to spray the whole area with suppressing fire. The MA5B also gives the user an ammo count on its digital readout, as well a compass pointing toward the arbitrary magnetic "north" position. In the hands of someone who can control their trigger finger, the MA5B becomes a deadly weapon in CQB situations.
The MA5B is not without disadvantages, the main problem being its horrible accuracy when fired at a range of more than forty meters. At that range, enemy infantry may be hit by a few bullets, or not be hit by any bullets at all. The MA5B Assault rifle performs poorly against energy shields unless firing on full automatic at close range without giving a shielded infantry time to recover. It also suffers from issues with jamming, due in part to its large magazine size. In comparison to modern Assault rifles it can be more related to an oversized sub-machine gun, as it is underpowered and lacks the ability to select a fire mode.
The MA5B Assault rifle is one of the weapons which users will love and loathe in equal measures. The rifle's rate of fire makes it a devastatingly powerful weapon in close range combats. The only disadvantage is it's reloading time, which takes about 1.5 seconds, allowing an opponent enough time to put a user down with a hail of plasma bolts. In a skilled user's hands, however, the Assault rifle can easily put down 2-4 opponents per magazine.
- The MA5B was heavily inspired by the MA-75B Assault rifle from the Marathon series.
- Robert McLees at Bungie has gone on record comparing the basic design of the MA5B to that of the Fabrique-Nationale, FN F2000. According to The Art of Halo, McLees didn't know of the F2000 until after the game was even finished; "I don't know when the images of the FN F2000 appeared, but I didn't see them until three or four months after the game shipped, and I thought 'Oh great. Now everyone's going to think I swiped the design from Fabrique National.' It was surreal to see how close the Halo Assault rifle was to its real-life counterpart... and it was all totally by accident."
- There is a second melee animation for the Assault rifle, in which the user holds the weapon vertically and clubs anyone in front of them with the back end of the weapon. This animation is used in a few Halo Custom Edition maps, but was taken out of the official game.
- In Halo: Combat Evolved, the compass on the MA5B points "north" to Threshold, seen in the sky. Since compasses operate on a magnetic principle, it is likely because Threshold provides the greatest nearby magnetic signal, and is arbitrarily designated 'north'. In Halo: The Flood, it seems that Ensign Lovell designated west randomly, at least prior to landing on Halo.
- In the Halo Graphic Novel, many Special Operations Unggoy and Sangheili are seen wielding Assault rifles, although the Covenant generally abhor the use of human weapons. The only other known instance of Covenant troops using human weapons was during the Battle of Installation 05, when several Jiralhanae were seen using Shotguns, although a Sangheili is known to have used an M6D pistol to execute the bridge crew of the Pillar of Autumn, albeit with much distaste.
- The Assault rifle is capable of killing up to 4 other players in multiplayer if every shot hit its mark. However, this is almost impossible to accomplish due to the weapon's inaccuracy.
- A comment made by Black Box in Halo: Glasslands seems to indicate that the MA5B is not as high-quality as the MA5C. It should be noted that the MA5B was replaced due a faulty spring and inaccuracy.
- In Halo: Combat Evolved Anniversary, the MA5B resembles the MA5C from Halo 3.