14.5×114mm

"High velocity, armor-piercing. They'll take the hat off an Elite at two thousand yards. And they ain't cheap."

- Jun-A266

The 14.5×114mm round is used by the United Nations Space Command's SRS99 series of sniper rifles. Multiple ammunition types are available in this cartridge.

Design
A modernized variant of an old ammunition type employed by the Soviet Union during the twentieth century, the round is employed in an anti-matériel role, used to damage or destroy enemy equipment and vehicles. However, thick Covenant armor, and the use of energy shields by Sangheili and Kig-yar, has also caused it to take on an anti-personnel role in addition to its anti-armor roles.

A round consists of perfectly shaped tungsten, enclosed in superhardened red polymer petals. On the base of the round, there is a winged hourglass flanked by a double "X", signifying that it is hand-loaded match-grade ammunition produced by Misriah Armory.

The 14.5×114mm 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 in the main trilogy, as rounds fired at vehicles and equipment will do no damage or ricochet. The round is best used on other combatants depending on their use of body armor and energy shields. The rounds leave behind a noticeable white vapor trail that can reveal the position of the sniper. However, this can also be used as an aiming aid for the sniper himself.

In Halo: Reach and Halo 4, the round is far more effective in an anti-vehicle role, doing effective damage to even heavier vehicles.

APFSDS
The 14.5×114mm APFSDS (armor-piercing, fin-Stabilized, discarding sabot) cartridge fires a long, thin subcaliber projectile (a projectile which is insufficient to properly grip the barrel interior of the weapon firing it) referred to as a "penetrator". To allow the projectile to function, it is contained while travelling down the barrel in a structural device called a "sabot", which keeps it centers it the barrel and is then discarded in flight. The projectile is stabilized in the air by a set of fins, increasing accuracy. Such ammunition is designed to harness dense, resilient materials and to maintain very high velocities in order to penetrate armor. The damaging capability of the 14.5×114mm round is impressive: at 600 yards the penetrator will go through about 13 feet of flesh and bone. The round is also highly potent at inflicting damage against light vehicles. Ammunition of this type which was utilized in 2557 aboard the UNSC Infinity with the SRS99-S5 AM sniper rifle bore the alphanumeric designation "M232".

HVAP
The 14.5×114mm HVAP (High Velocity, Armor-Piercing) round is substantially different from the APFSDS round: While 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 high-density, hard material surrounded by a full-bore shell of a lighter material such as an aluminium alloy.

HVAP rounds lose velocity and accuracy at long ranges, giving rifles firing this round 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.

HEAP
The 14.5×114mm HEAP (High-Explosive, Armor Piercing) round is used by Linda-058 in her personal modified rifle Nornfang. These rounds explode violently on impact, dealing a great deal of damage to the target.

Trivia

 * Currently the term "APFSDS" is reserved for large tank-mounted weapons. In small arms such as the sniper rifles used in Halo, it is called a flechette.
 * The Steyr ACR is a real-world prototype weapon that was designed to fire a 5.56mm flechette, similar to the 14.5mm APFSDS used in Halo. However, this weapon is a select fire assault rifle, rather than a sniper rifle.
 * The 14.5×114mm is actually a Russian heavy machine gun round that was developed for use in anti-tank rifles like the PTRD and PTRS in World War II, later used in Anti-Aircraft and Vehicle-Mounted roles with the KPV; it remains in use to this day.

List of appearances

 * Halo: The Fall of Reach
 * Halo: Combat Evolved
 * Halo: The Flood
 * Halo: First Strike
 * Halo 2
 * Halo Graphic Novel
 * Armor Testing
 * Halo: Ghosts of Onyx
 * Halo 3
 * Halo: Contact Harvest
 * Halo: The Cole Protocol
 * Halo Wars
 * Halo 3: ODST


 * Halo Legends
 * Homecoming
 * Prototype
 * The Babysitter
 * Halo: Blood Line
 * Halo: Fall of Reach
 * Boot Camp
 * Invasion
 * Halo: Glasslands
 * Halo: Combat Evolved Anniversary
 * Halo 4
 * Spartan Ops
 * Halo: Spartan Assault
 * Halo 2: Anniversary
 * Hunt the Truth
 * Halo 5: Guardians
 * Halo: Fractures
 * Breaking Strain
 * Halo: Envoy