High explosive ammunition
From Halopedia, the Halo wiki
High explosive ammunition, or simply HE ammunition, is a type of ammunition designed to penetrate armor through the use of explosive material.
In HE ammunition, an explosive compound is added or mixed in with the standard type of gunpowder. After the bullet has been fired from the weapon and has hit a target, the compounds inside the round will ignite and detonate, thereby creating a potentially larger entry wound, a deeper impact wound, and a dangerous exit wound. The rounds are therefore useful for placing exact shots at the more vulnerable parts of the body, such as the head and torso.
HE ammunition is effective in both anti-matériel and anti-armor purposes, capable of cutting through both flesh and alloy with ease. It is most often used in anti-vehicle weapons, where its explosive capabilities renders it particularly effective against alloy steel. HE ammunition is also available for small arms, such as the M225 Semi-Armor-Piercing High-Explosive which is used in the M6 series of sidearms. The Office of Naval Intelligence employs a type of HE ammo known as High Explosive Dual Purpose ammunition in its security forces' specialised vehicles and weapon emplacements.
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