|There is more information available on this subject at 14.5x114mm on the English Wikipedia.|
Possibly similar to an 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 caused it to take on an anti-personnel role in addition to its anti-armor roles.
The 14.5mm sniper round has less effect on living targets due to the ammunition type. These are designed for penetration and not terminal performance; this type of bullet does not fragment nor does it tumble, which would cause maximum damage to a target but instead punches through with extreme velocity, so the actual wound it creates is rather unimpressive, at least compared to that of a weapon firing rounds that would tumble or fragment. APFSDS rounds were originally intended for use in armor vehicle main weapons (IE 90mm-120mm smoothbore guns) to defeat armored vehicles due to the increasingly ineffectiveness of HEAT and HESH shells against modern armor, though many other large caliber weapons have seen use with it.
- The 14.5x114mm round 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.
- Its armor piercing capability is evident when a single bullet fires through multiple Spartans and Sangheili with full Energy Shields.
- The round bears striking similarity to the 14.5 and 15.2mm APFSDS rounds developed by Steyr-Mannlicher AG & Co KG in the mid 1980s for their AMR 5075 and IWS 2000 sniper weapons.
- This type of round is a .57 caliber, much bigger than the 12.7x99mm (.50 BMG) the M41 LAAG uses.
- By roughly scaling from similar real-world KEP-type ammunition like the 120mm M829, we can assume that the 14.5mm APFSDS has a tungsten subcaliber penetrator with dimensions of ~8.8×88mm and a mass of 103g, possesses a muzzle velocity of ~1530 m/s (Mach 4.5), muzzle energy of ~120,556 J, momentum of ~157.59 N·s, and penetration of ~170mm of RHA at 90° from 1500m. This is far greater than the M903 SLAP's 7.7mm, 23g penetrator with its velocity of 1220 m/s (Mach 3.58), muzzle energy of 17300 J, momentum of 28.06 Ns, and penetration of ~19mm of steel RHA at 90° from 1500m. Given the fact that an APFSDS is not exactly similar to a SLAP in construction, such a comparison is not entirely fair; however, they are close enough for a rough idea to be gained.