14.5×114mm
From Halopedia, the Halo wiki
The 14.5x114mm Armor-Piercing Fin-Stabilized Discarding-Sabot bullet is used by the United Nations Space Command's Sniper Rifle System 99C-S2 AM and Sniper Rifle System 99D-S2 AMs. Possibly similar to an ammunition type employed by the Soviet Union during the twentieth century, the round is employed in an anti-material role, used to damage or destroy enemy equipment and vehicles. However, thick Covenant armor, and the use of energy shields by Elites and Jackals, has caused it to take on an anti-personnel role in addition to it's anti-armor roles.[1][2]
It also bears striking similarity to the 14.5 and 15.2mm APFSDS rounds developed by Steyr-Mannlicher AG & Co KG in the mid 1980's for their AMR 5075 and IWS 2000 sniper weapons.[3]
In-game, the 14.5mm sniper round is massively underpowered. The fact that Covenant life-forms can realistically survive a hit from such a powerful round is debunked by the fact that the bullet travels through the body and can hit another enemy. If that were the case, the round should leave a massive, gaping hole in the body, undoubtedly killing or seriously wounding the enemy combatant. However, that statement is overlooking the ammunition type- APFSDS, or "Armor-Piercing, Fin-Stabilized, Discarding-Sabot" rounds are designed for penetration and NOT terminal performance, meaning that they would be like shooting a nail at someone (as you can see in the images above, they look like nails with fins). This type of bullet does not fragment nor does it tumble but instead punches through with extreme velocity like a hypersonic drill, so the actual wound it creates is rather unimpressive compared to the standard. It is intended for use in armor vehicle main weapons (IE, 30mm autocannons and 120mm smoothbore guns) to defeat armored vehicles due to the increasingly ineffectiveness of high explosives against modern armors. Even so, getting hit with a round that would generate around 25,000 joules of muzzle energy at 1500 meters per second muzzle velocity would be unpleasant to say the very least, and being struck in the head would be lethal due to the sheer lateral pressure it would produce around it and the vaccuum it would generate behind it, especially if you had a helmet on, because it would cause the metal in the helmet to fragment inwards.
Trivia
- The 14.5x114mm round in reality is a Russian Anti-Tank and Anti-Material heavy machine gun round. Take a look at this page for more information.
- This is only the default ammunition size for the sniper. It can use other ammo types, one being a .480 or .450-caliber round.
