M-201 Scout Sniper Weapon System

"This thing is way lighter than the 99s, but I wish they'd make into a semi-automatic."

- Sergeant Travon Gallagher, 153rd Ranger Regiment

The M-201 Scout Sniper Weapon System (known officially as the 14.5x100mm, UNSC Model-201/Alpha-Variant Scout Sniper Weapon System or colloquially as the Phalanx Sniper Rifle) was a sniper rifle system manufactured by the government-operated defense contractor Horizon Armory. It was often renowned rifle in the hands of snipers affiliated with the United Nations Joint Armed Forces Command.

In 2559, five years after the M-201's initial production run, the M-201B debuted in field operations; the most notable change for the M-201B was the overhaul from a bolt action system to one that was semi-automatic. This second iteration would eventually outproduce its predecessor by nearly three-and-a-half times; its service length would also last for for forty-two years, twelve more than that of the M-201A.

Design
The Phalanx was designed to be the "sniper's lightweight yet powerful friend." Whereas many sniper rifle systems of the current era were manufactured from durable albeit weighty alloys, much of the M-201 is composed of Carbonide, a tough, lightweight carbon-based polymer invented by scientist Alfred Jameson-Boren during w:c:halo:Operation: TREBUCHET and perfected by UNSC-backed scientists in the 2540s. This choice of material improves the frame's strength-to-mass ratio by eighteen percent.

While the M-201A's bolt action operation system did limit the firing rate, it also prolonged the barrel's lifespan to near-infinite (providing it receives ideal care), improves the strength-to-weight ratio, and even accuracy-to-value ratio to an extent. However, more mobile and accessible rifles prevented the Phalanx from attaining any squad support or designated marksman role. This is often considered the primary reason for the major changes seen with the M-201B.

In addition to the aforementioned aspects, the M-201 series' barrels utilized octagonal polygonal rifling as opposed to the more common "conventional" rifling. Not only does this technique, which hasn't been seen in production firearms since the 2470s, prolong the life of the barrel to an extent and limit required maintenance, but it also provides a better gas seal around the projectile as polygonal bores tend to have a slightly smaller bore area, which translates into more efficient use of the combustion gases trapped behind the bullet, slightly greater (consistency in) muzzle velocities, and slightly increased accuracy.