High-explosive incendiary

In warfare, high-explosive incendiary is a type of ammunition specially designed to impart energy and therefore damage to its target in one or both of two ways: via a high-explosive charge and/or via its incendiary effects. Each round—by definition—has both capabilities.
HEI ammunition is fused either mechanically or chemically. The armor-piercing ability can vary widely, allowing for more focused fragmentation or larger scatter.

History

HEI ammunition was originally developed for use in large-caliber cannon, howitzer and naval artillery. Currently, HEI rounds are most commonly made in medium-caliber sizes of 20 [mm caliber|20], 25, 30, and 35 mm. They are fired from various platforms, including aircraft, anti-aircraft cannons, and anti-missile systems.
HEI ammunition has also been used on the battlefield against tanks and other armored vehicles, but mostly in a last ditch attempt to disable external components.

Uses

[Image:30mm-rounds.jpg|thumb|The shell on the left is a 30 mm HEI]
HEI rounds are mainly used in incendiary rounds against softer targets such as aircraft, infantry, and unarmored vehicles.