High Explosive Dual Purpose

High Explosive Dual-Purpose (HEDP) is a type of warhead that combines armor penetration ability with a fragmentation effect that can injure or kill softer targets in a wider area. HEDP warheads are typically found inside Launched Grenades as well as some Light Anti-Tank Rockets. It provides a weapon with the ability to tackle a variety of threats, including both Enemy Infantry and Light Vehicles - up to and including Armored Cars and some APCs.

An HEDP is mostly a normal HEAT warhead, also known as a "shaped-charge", which can direct its entire power into a single point of armor in order to pierce straight through it and destroy whatever is inside. The difference is that the casing containing the explosion is designed to break apart into multiple small fragments, which scatter in every direction. This combination creates the armor-piercing/anti-infantry effect that makes these warheads so versatile.

HEDP is a good option for Infantry; they are likely to encounter a variety of different targets and therefore benefit from weapons that can handle different targets. However such explosives are less-than-optimal at handling any specific type of target.

The most common HEDP warhead in ShackTac is the 40mm grenade launched by Grenade Launchers, which is normally carried by every Fireteam Leader, Squad Leader and Platoon Leader. It is typically used to attack groups of infantry at range. Another variety is the HEDP rocket available for the SMAW, though it has not been seen used in ShackTac videos so far. Most Light Anti-Tank Launchers and Medium Anti-Tank Launchers fire HEAT or Tandem warheads instead, since they are much more likely to be needed to fight off armored vehicles.

Design
HEDP was invented in the United States during the Vietnam War. Its purpose is to provide a versatile explosive that has better armor-piercing properties than regular High Explosive or Fragmentation grenades, while retaining its ability to hurt or kill Enemy Infantry within its blast radius. The compromise was to create a HEAT warhead that also channeled part of its explosive power into splitting apart the casing of the warhead, flinging its fragments at high velocity in all directions.

This design was first implemented into the 40mm grenades launched by the M203 under-barrel grenade launcher designed for the M-16 rifle. With this quick-to-use attachment weapon, soldiers could easily switch between firing bullets and firing grenades, and removed the need to carry a separate grenade launcher on one's back. At a moment's notice, a soldier carrying the M203 could engage an approaching vehicle - up to and including certain APCs - or launch a grenade at a cluster of enemies. HEDP can also be used to attack infantry behind light cover, such as thick trees, and can also be fired into a building or bunker from a considerable distance.

This versatility comes at a cost: An HEDP warhead is not as good as penetrating armor as HEAT warheads, and does not have as much of a kill radius as Fragmentation warheads. Previous versions of ArmA also had trouble modeling the warhead's fragmentation capabilities, resulting in an unreliable effect that could fail to kill anyone even within a very short distance of the impact point. Nevertheless, a barrage of HEDP grenades is usually likely to kill at least a few of its targets, and players have occasionally used these warheads to damage APCs and even the occasional IFV to the point where the crew decided to abandon the vehicle.

Later in the 20th century, the SMAW Medium Anti-Tank Launcher was also provided with an HEDP rocket, giving that weapon a dual-purpose ability. However, this rocket has not so far been seen in ShackTac, as MAT units are expected to conserve their rocket exclusively to defeat heavy armor, and thus are provided solely with HEAT rockets.