The SRS99 AM is a gas-operated semi-automatic UNSC sniper rifle that fires 14.5 x 114mm APFSDS (armor piercing, fin-stabilized, discarding sabot) from a 4-round magazine. It is designed in the conventional layout, so the magazine and operating system are located in front of the trigger. The magazine does not fit flush.
The SRS99D is about 187.5 cm 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. The SRS99D in Halo 3 has some notable changes from the SRS99C models. First off, it is fitted with a 5x and 10x optic that shows real time images in infrared vision when not looking through it. When looking through it, the scope shows a target's distance and elevation. The SRS99D also has an altered foregrip, stock, body and sports a trigger guard. The barrel also now has an iron sight. This weapon does not possess a safety and has a frame that serves as a carrying handle as well as a scope protector and a folding bipod located in front of the magazine on the underside of the rifle.
The SRS99D has one of the most advanced ammunition types in the game. Its rounds are large in both length and width, and are equipped with four symmetrical fins on the sides of the round, stabilizing its trajectory to results of amazing accuracy, with a hit ratio of 97.3%. While these fins provide increased accuracy, they also prevent a seal from forming between the bullet and barrel. A sabot is used to plug up this empty space, and is forcefully discarded from the bullet upon leaving the barrel. The 14.5mm APFSDS round has a muzzle velocity of 1450 m/s.
The rounds themselves were inspired by the 14.5 x 114mm Russian-made projectile, used primarily in HMGs and sniper rifles. The rounds are described as being made of very hard metal, so they are probably made of tungsten or a depleted uranium alloy for maximum penetration. Despite the round's designation of "Armor-Piercing," it is woefully inept in the anti-armor role, scarcely capable of damaging even the light-skinned vehicles commonly encountered in the Halo series, and is typically only useful against vehicles if a clear shot on the driver is available.
Many contemporary weapons and ammunition used against Covenant armor and shielding systems would seem ineffective; this is why most UNSC firearms use large types of ammunition because they are mostly used for their effectiveness in armor penetration and kinetic energy. However, in both Halo: The Fall of Reach and Halo: First Strike, there are several in-book references to standard UNSC personnel and the Spartans using the SRS 99C-S2 even before humanity had learned of the Covenant's existence. This is odd, as the ammunition is so large and complex for use on a human target - the modern-day equivalent would be using a Barrett M82 .50 BMG anti-matériel rifle specifically against regular infantry, or the PTRS-41 WWII era anti-tank rifle for the same purpose.
The rifle uses a 4-round magazine, and operators typically carry meager combat loads; 28 rounds, or 7 magazines total in Halo: Combat Evolved, 24 rounds or 6 magazines in Halo 2 and Halo 3. However, a "full combat load" was described in Halo: First Strike, and in the Halo: Combat Evolved level Truth and Reconciliation you start with a Sniper Rifle and a 68 round load, although this was obviously for game play purposes, as it was an extremely marksmanship-intensive level.
The SRS99D-S2 AM, as an anti-matériel sniper system, is an extremely effective weapon. The terminal ballistics profile of the 14.5 x 114mm round is impressive; at 600 yards a round from the SRS99D would go through about 13 feet of flesh and bone. Its precision and lethality make it a choice weapon for almost any combat situation. At close range the user can shoot and melee attack quickly; at mid-range if a head shot is not possible then a body shot followed by another head shot would be effective, and at standoff range, there are few weapons that would be a danger to the user.
Even in the hands of a player not quite skillful enough to perform one shot kills, the sniper rifle's ability to down an enemy player's shields provides a sound tactic for keeping the enemy at bay, and for other players to take down the enemy. This weapon also can be used for map control as it limits where the enemy can go, often forcing them to stay in hiding spots for fear of being shot as soon as they go out into the open. This can help the team gain more strategic advantages like getting power weapons or securing good defending positions. It also acts as a support weapon, and can help the team achieve easy kills by leaving enemies with no shields. Another advantage of the weapon is its relatively quick reload time compared to other weapons like an Assault rifle. The rounds fired meet their target almost instantly even at extreme ranges. They can ricochet around corners, and are able to hit multiple targets if they are lined up properly.
A sniper usually needs to find a safe location to shoot from, as the Sniper Rifle's rounds leave behind a white trail of vapor. If the player is spotted by an enemy player, they will most likely attempt to get close and kill the sniper with a close range weapon. The Sniper Rifle is somewhat useless in close range combat, unless you can perform what is commonly referred to as a no-scope kill. Due to having more recoil than its predecessor, using the Sniper as a long range weapon is much harder than it was in Halo 2, although at close range the difference is negligible because the target appears to be larger. If the user is too far away and firing while not sighted-in, they can easily miss.
Also, because there are only four rounds per magazine, a user with the sniper rifle has to reload frequently. Because of its incredible strength, ammunition on any map for the sniper rifle is rare. The Sniper Rifle is also very loud, so if an enemy is near, but cannot see you, it will give your position away. The greatest disadvantage of the sniper rifle is the skill required to use it, a player must be very accurate and have good eyesight and reflexes, especially when trying to go for head shots; another unfortunate disadvantage is that because of its power and the allure of being a good sniper, the sniper is often hotly contested, even among teams.
Changes from the SRS99C in Halo 2
- Overall higher damage and slower fire rate.
- New muzzle brake with front iron sight.
- Hand guard, body, and stock has been altered.
- The scope now shows real-time with an LCD screen and infrared vision.
- It now has a trigger guard.
- The SRS99D-S2 AM now has a new flat matte black color finish to it.
- Recoil affects aim.
- Main article: Sniping
- In the Halo 3 mission Sierra 117, there is a downed Pelican at Rally Point Alpha. There is a UNSC supply box with two sniper rifles. These can be useful when you get to the dam.
- After you cannot proceed any further on Warthogs and have to jump a broken highway section on the Tsavo Highway, there is a sniper rifle located above the entrance to the next area, accessible by taking the path towards the right of the entrance.
- After the Hunter encounter on The Storm where you must face a hammer wielding Brute Chieftain, the room to the far left contains a sniper rifle. Breaking the window will allow you to snipe Covenant forces.
- Because the Sniper Rifle has such a small magazine and limited ammo supplies, it isn't worth using it against weaker enemies like Grunts and Jackals. However, the Sniper Rifle's penetration capabilities and superb long range accuracy make it excellent for killing higher ranking enemies at long range like Brutes and Hunters, which, in turn, disorganizes and demoralizes the enemy troops, making combat against a large ground force easier.
- Sniping fallen grenades when enemies are close by is also an effective strategy.
- Sniping is easier if you turn down your look sensitivity. Unfortunately, this makes the shotgun and other close quarters combat weapons slightly harder to use in a chaotic environment.
- If an enemy turns out to be very difficult to hit, don't waste a round on them. Wait until they're an easier target, or just switch your attention to another target.
- Have a sniper set their sights on the enemy base in a CTF match, as they can take out enemy snipers and other defenders. That way, their team mates can swoop in and grab the flag.
- If you can get a couple of players to cooperate, you can get to hard-to-access areas on maps like Valhalla, Longshore and Last Resort and snipe without having to worry about close range weapons trying to flush you out.
- The Sniper Rifle shot can be used in close combat as a shield remover, followed by a melee which will kill your opponent.
- If you don't feel like moving to a new position after you take a shot, you should at least find a good piece of cover.
- Always take your shots carefully with the sniper rifle. If you are unable to perform headshots, always aim for the body. The key to sniping is simply getting the kill, not getting a headshot every time.
- A tactic performed by professional snipers today is to move from location to location after each kill or round fired, never revealing your location.
- Catching snipers - assuming someone isn't watching their back - is easy. When they are compromised, they usually panic, burning off a few rounds in an attempt to no-scope the enemy.
- If you do camp, you should have only one person guarding your back. More than one person guarding you can look like a big threat if an enemy spots all those people.
- If you are good at shooting without your scope, or are simply looking for a power weapon, find the sniper on tight quarters maps like Construct, Foundry, Orbital and Ghost Town . Players will often ignore a sniper on these maps.
- Another tactic is having one player with a sniper rifle and another with a close to mid-range weapon. The player with the close ranged weapon helps spot targets and defends the sniper from close range attacks.
- Always carry a secondary close ranged weapon such as an Assault rifle or SMG. Even more preferable are a Shotgun or a Battle Rifle.
- Watch your back. If you become absorbed in the scope on your rifle, you may allow someone to splatter or assassinate you. Break out of zoom if you hear the someone reloading or approaching.
- Sometimes the best place to snipe is out in the open, away from the fight. However, after you fire a shot you are immediately exposed due to revealing your location.
- When you are in close combat with a sniper but you are scoped in, a quick way to get out of scope is by quickly pressing the Y Button twice. This will take your view out of scope. Another way is to melee, though this will leave you vulnerable to nearby enemies.
- Watch the Man Cannons when holding a sniper rifle; if another player jumps on it, you can usually pull off an easy head shot.
- When playing Team Snipers, take your shot and then move elsewhere, so your location is not given away.
- Combine the sniper with a Spartan Laser and you have a very good anti air/vehicle/infantry class.
- The max range of the scope's range finder is approximately 275m. The max distance the reticle will turn red on enemies is approximately 142m.
- In Halo: Combat Evolved and Halo 2, a cyan logo identical to the "trinity" emblem can be found on the stock of the Sniper Rifle System 99C-S2 AM. However, in Halo 3, the emblem is absent from the SRS99D. In part 1 of the Arms Race video trilogy, the SRS99D can be seen being made at Misriah Armory on Mars. However, the "Trinity" logo is seen on the rifle in the Halo 3 game booklet as well as in the Arms Race Part 1, where it is found on the stock of the "second" rifle in the magazine, and in part 3, it is visible on the stock of the rifle when T. Rymann uses it to kill the Brutes.
- Sniper Rifle System 99 Anti-Matériel (Halo: Reach)
- Sniper Rifle System 99C-Series 2 Anti-Matériel (Halo: Combat Evolved)
- Sniper Rifle System 99C-Series 2 Anti-Matériel B (Halo 2)
- Type-50 Sniper Rifle System (Covenant equivalent)