SRS99C-S2 AM sniper rifle

The Sniper Rifle System 99C-S2 Anti-Matériel, abbreviated as SRS99C-S2 AM and commonly known as the SRS99C-S2 AM Sniper Rifle, is a standard-issue service sniper rifle of the United Nations Space Command. It made appearances in Halo: Combat Evolved, Halo 2, and Halo Wars.

Design details
The SRS99C-S2 AMB is a semi-automatic, gas-operated sniper rifle that fires 14.5mm x 114mm APFSDS rounds from a 4 round magazine. It is designed in the conventional layout, so the mag and operating system are located in front of the trigger. It is, alongside its Covenant counterpart the Particle Beam Rifle, the most accurate and arguably the most powerful small-arms weapon in both arsenals. The rifle features a barrel about 187.5cm long and is completely interchangeable. From the barrel to the breech to the stock, everything can be changed to fit the current situation and satisfy the operator.

Ammunition
The SRS99C-S2 AM fires the 14.5x114mm APFSDS (Armor-piercing, fin-stabilized, discarding sabot) rounds semi-automatically from a standard four round magazine. These rounds are large in both length and width and are equipped with four symmetrical fins spaced equidistantly around the base of the projectile, stabilizing its trajectory to results of amazing accuracy, with a hit ratio of 97.3%.

The rounds are described as being made of very hard metal, with the core probably composed of tungsten or depleted uranium, like most anti-matériel ammunition today. The APFSDS 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 poorly in this role, as rounds fired at vehicles and equipment will do no damage or ricochet. The round is best used on other combatants depending on their combat system (Body armor, energy shields, etc). The APFSDS rounds fired by the SRS99C-S2 AM leave behind a noticeable white vapor trail that can reveal the position of the sniper, however they can be used as an aiming aid for the sniper himself.

Advantages
The SRS99C-S2 AM is designed to be used at medium to long ranges and is equipped with an electronic scope for precisely this purpose. It has two variants; the SRS99C-S2 AM has a 2x and 10x zoom in the Xbox version of Halo: Combat Evolved and a 2x and 8x in Halo PC, while the SRS99C-S2 AMB of Halo 2 has a 5x and 10x zoom. 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, its most useful application in campaign mode is taking out the higher-ranking enemies in a group to destabilize their squad's discipline and morale. A headshot against any Covenant infantry except a Zealot, Major Domo Elites, Ultra Elites. Hunters fall from one shot to their unarmored torso or neck. This does not account for Flood, however, due to the body organization as explained in detail in the Disadvantages section. The Flood can, however, be rendered harmless by removing their limbs or by placing a round into the embedded Infection Form. In multiplayer, the SRS99C-S2 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 SRS99C's projectile has a slight 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 Grunts. The SRS99C is also largely ineffective against most Flood forms, due to their body organization; damage done by the SRS99C is minimal to the Flood forms and would only cause the Flood form to flinch for a moment. It is often recommended for operators to simply switch to other weapons should they encounter a Flood form.

As explained previously in the ammunition section, rounds fired by the SRS99C would 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.

Influence
The SRS99C-S2 appears to be heavily inspired by (if not directly copied from) 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.

In addition, the round (14.5 × 114mm) is an actual rifle cartridge, developed by the Russian Army for anti-tank rifles, heavy machine guns, and sniper rifles. However, the real 14.5 mm round has a standard cartridge design, whereas the round used in Halo is an APFSDS round (armor-piercing, fin-stabilized, discarding sabot).

The influence for a muzzle brake at the end of the SRS99C-S2 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 SRS99C-S2'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.

SRS99C-S2 AMB
The Sniper Rifle System 99C-S2 Anti-Matériel B, abbreviated as SRS99C-S2 AMB Sniper Rifle is an upgrade of the SRS99C-S2 AM Sniper Rifle found and is usable in Halo 2. The AMB variant includes a different scope and a better designed grip for stability and accuracy.

It was first mentioned in Halo: Ghosts of Onyx, when Petty Officer Second Class Linda-058 used it at Havana during the Battle of Earth and later during the Battle of Onyx.

Changes from Halo: Combat Evolved to Halo 2

 * Minor cosmetic changes.
 * Shorter overall length.
 * Decreased max magazine capacity down from 28 to 24.

Tactics
The SRS99C-S2 AMB is extremely powerful, but with a small combat load, it is not good practice to use this weapon against weaker enemies (Grunts, Drones). However, the SRS99C-S2 AMB penetration capabilities and superb, long range accuracy makes it excellent for killing higher ranking enemies at long range, which, in turn, disorganizes and demoralizes the enemy troops, making combat against a large ground force much easier.

Campaign

 * Take cover behind any rock or building (if any). Easily take aim and make sure you fire before the hostile sees you. Also stick to high ground (if any). Do not waste rounds on minor threats like Unggoys (Grunts) or shield bearing Kig-Yar (Jackals) since ammo is usually scarce and you can kill them easily with other weapons too. Even from a distance, the pistol can usually take care of them in one headshot.
 * A good setup in covenant levels is to take SRS99C-S2 AMB for longer range and difficult foes, such as Sangheili (Elites). Secondary weapon can be anything you feel good to take out minor foes like Jackals and Grunts. The M6D pistol is an excellent secondary weapon, because of the accuracy, stopping power and zoom function. This pistol negates the need of SRS99C-S2 AMB for longer ranges, thus saving its scarce ammo, so you can use it against zealots, ultras, major elites etc.
 * In Flood levels, the SRS99C-S2 AMB should be ignored, as the rounds pass throught combat and carrier forms, doing little to no damage at all. However, in levels that inculde both enemies (covenant and flood), one could bring the SRS99C-S2 AMB for covenant enemies and the M90 Close Assault Weapon System (or other weapon that the player feels good to use againts flood), to maximise damage againts both foes.
 * When combined with a Plasma Pistol, the SRS99C-S AMB2 can be used to form a special kind of noob combo, with the overcharged Pistol depriving enemies of their shields and the SRS99C-S2 AMB dealing a fatal body- or headshot. This variant is more powerful than the combination of a Plasma Pistol and an M6D Pistol, however it is more advisable to replace it with the M6D when available, for the SRS99C-S2 AMB is too valuable to use it against weaker enemies, has a smaller clip and overall ammo capacity and a slower rate of fire than the M6D.

Multiplayer Recommendations

 * In Halo: Combat Evolved, effective use of the SRS99C-S2 AMB in multiplayer takes a lot of practice. It is necessary to aim in front of a target to accommodate for server lag, how far one should aim in front depends on their angle onto the target and the amount of lag in the server. Targets are shot easiest when they are head on, moving directly toward you.
 * A head-shot will kill an enemy outright, regardless of shield. Night vision is best used in dark areas (obviously) but is useless in maps that have high color contrast. Good secondary weapons include the M6D Pistol which can, when shot accurately dispose of an enemy in 3 shots regardless of shield. Its 2x zoom make it the perfect partner for the SRS99C-S2 AMB.
 * Use natural formations and buildings to snipe from, but move constantly and erratically (including jumping and crouching) to lower the effectiveness of counter-sniping. The fact that 14.5x114mm APFSDS bullets leave a smoky trail is the weapons largest downside (apart from the small magazine capacity) it exposes one's position and alerts the enemy easily; constant position changing is advised to confuse the enemy. Find something to hide behind while you reload, and reload when not in a firefight. Good snipers cover teammates and kill anyone who is chasing the person on your team with the flag (note: this is only for CTF).
 * Sniping is easier if you turn down your look sensitivity. Unfortunately, this makes shotgun and other close quarters combat weapons slightly harder to use in a chaotic environment.

Trivia

 * Linda-058 changes the sniper's ammo size to .450-caliber in Halo: The Fall of Reach. In fact, she shoots more rounds than simply four bullets at a time.
 * In the novel Halo: Ghosts of Onyx, the SPARTAN-IIs and IIIs utilize grapple rounds in place of standard ammunition. These rounds are described as harpoon-like shafts attached to braided monoline rope which is coiled in a bag.
 * "Robert McLees is definitely the go-to guy for the gun stuff," says William O' Brien, part of Halo 2's animation team, "I wanted to come up with an animation for the sniper scope, an 'idle cycle'. If you activate the scope, and then sit too long without doing anything, the animation would kick in periodically, just to keep things interesting... Simple, right...? He replied, 'No way. If you adjust your scope in the field, you're dead. Snipers don't do that.' That's how detailed his weapon designs are -- not just guns, but how they work, and how a sniper would fire them. Amazing."
 * In Halo: Combat Evolved, enemy AIs do not acknowledge the sniper rifle's shot if they do not see the sniper, despite its loud crack in close-medium quarters. If the player down an enemy with the sniper rifle, some will note the fallen AI, but will not search for the player as they would if the player fired with any other weapon.
 * One possible reason that the Halo: Combat Evolved Sniper Rifle has a night-vision setting is that, like the rest of the equipment available on board, was upgraded for the Spartans' mission. Also, Linda-058 needed specialized equipment, so the stock of snipers may have been upgraded for her.