SRS99-AM sniper rifle

The Sniper Rifle System 99 Anti-Matériel, more formally known as the Special Applications Rifle, Caliber 14.5 mm, SRS99, is a United Nations Space Command sniper rifle. The SRS99 first entered service with the Army in 2460. Because of its modularity and ongoing manufacturer support, the SRS99 was adopted by all branches in 2521.

Design details
The SRS99 is a semi-automatic, gas-operated rifle that fires 14.5x114mm ammunition from a four-round detachable box magazine. The ejection port is on the right side of the weapon and the charging handle is on the left side. Unlike all other known models of the SRS99 series, this variant features a thumbhole stock instead of a pistol grip, and its body sports a black and navy blue finish in addition to the gray of its successors. Also unlike its successors, it can be seen utilizing a sling-mount in-game. The SRS99's scope is similar to the SRS99D-S2 AM's scope, as both display green outlines of objects.

Ammunition
The SRS99 fires 14.5x114mm HVAP (high velocity, armor-piercing) rounds semi-automatically from a standard four-round magazine. These rounds are substantially different to the APFSDS (armor-piercing, fin-stabilised, discarding sabot) fired by the rest of the series: APFSDS rounds are sub-calibre, dart-like projectiles with a breakaway sabot surrounding an arrow-like bullet. HVAP rounds are full-bore rounds consisting of a core of a high-density, hard material surrounded by a full-bore shell of a lighter material such as an aluminium alloy.

The HVAP round is an anti-matériel munition, meaning that it is specifically designed for use against military equipment rather than against other combatants. It performs rather well in this role and can take down any vehicle with enough rounds, though it is still nowhere near as effective as heavy weapons such as the Rocket Launcher and Spartan Laser. That said, he rounds are best used on other combatants depending on their use of body armor and energy shields. The HVAP rounds fired by the SRS99 leave behind a noticeable white vapor trail that can reveal the position of the sniper. However, it can be used as an aiming aid for the sniper himself.

The weapon can also be quickly and easily chambered to utilize other ammunition types, such as the .450 cartridge. The weapon can also fire grappling hooks rather than standard ammunition.

Advantages
This rifle is designed to be used at medium to long ranges and is equipped with an electronic scope for precisely this purpose. It is tremendously useful in its designated role, considering its extraordinary range, surpassing any other weapon of comparable size, and its incredible stopping power even against body armor and Covenant shielding system.

By far, one of its most useful applications is taking out higher-ranking targets from long range to destabilize their squad's discipline and morale. A headshot will kill any Covenant infantry except a high-ranking Elite or Brute. Hunters fall from one shot to their unarmored torso or neck. The rifle can be highly effective at close range in the hands of a skilled operator, as the highly damaging round is just as powerful at close range; a single round followed by a melee strike will kill a hostile almost instantly.

Disadvantages
The rifle's projectile has a noticeable travel time at great distances, and requires practice to use effectively at range. When used in close quarters, its precision nature, slow reload time, small magazine capacity, heavy recoil, and slow rate-of-fire leave absolutely no room for error. A small combat load and the relative scarcity of ammunition available for the weapon also make it bad practice to expend ammunition on smaller, less threatening combatants such as Unggoy.

The HVAP rounds fired by the SRS99 leave a trail that could be traced back to the sniper's location. The rifle is fatally ineffective against even light-skinned and unarmored vehicles (belying its designation as an anti-matériel weapon) unless a shot can be taken on the vehicle's occupants, except for Wraiths. Furthermore, HVAP rounds lose velocity and accuracy at long ranges, giving this rifle an effective range of roughly 1800 metres, considerably less than the 2300 metre ranges of the later-developed, APFSDS-firing SRS99C-S2 and SRS99D-S2 rifles.

Influence
The SRS99 appears to be heavily inspired by the South African NTW-20 and the Barrett M107 SASR. Many of the features present in the Halo version are included in both weapons, such as the recoil-dampening piston, the general appearance of the receiver, the magazine placement, muzzle brake and many other attributes.

The influence for a muzzle brake at the end of the rifle comes from many different current sniper rifles, namely the Barrett M107 SASR. However on the Barrett M107, the gasses are forced out of the muzzle brake diagonally away from the barrel and towards the shooter. This helps to significantly dampen the recoil. The rifle's muzzle brake is shaped so that the expanding gasses are forced out the muzzle brake and away from the shooter. This would slow the round's muzzle velocity, and significantly increase the recoil by around forty percent.

Changes from the SRS99D-S2 AM (Halo 3)

 * Increased damage against vehicles, destroying them with four to six rounds.
 * Has a thumbhole stock rather than a pistol grip.
 * More detailed appearance.
 * Updated colors.
 * Scope is smaller compared to the rest of the rifle.
 * Can neutralize a Scorpion tank in two shots, one to destroy the canopy, and a headshot to kill the now-exposed driver.

Trivia

 * In the Halo: Reach Multiplayer Beta, the scope shows the identity of the weapon's user as "ID-NOBLE6", regardless of who wields it. This has been removed in the final build.
 * At the beginning of the level Nightfall, the player receives fifty rounds instead of the default maximum of twenty. This is a tribute to the level The Truth and Reconciliation from Halo: Combat Evolved, in which the player begins with a larger-than-normal number of sniper rifle rounds.
 * The weapon's reticle bloom has almost no effect on gameplay. However, its accuracy is not 100% perfect due to bloom. This can be proven by enabling the Bottomless Clip option in gametype settings, then firing the rifle as fast as possible. Eventually, the reticle will be fully expanded, proving that each shot is very slightly skewed, and is only noticeable if bottomless clip is enabled.
 * As opposed to other sniper rifles in the series, the SRS99 is rather worthy of its anti-materiel designation, as it will quickly destroy most vehicles, and can destroy a Wraith in a single clip under certain circumstances.

List of appearances

 * Halo: Reach