Editing Terminal ballistics (section)

===Large caliber===
The purpose of firing a large caliber projectile is not always the same. For example, one might need to create disorganization within enemy troops, create casualties within enemy troops, eliminate the functioning of an enemy tank, or destroy an enemy bunker. Different purposes of course require different projectile designs.

Many large caliber projectiles are filled with a [[high explosive]] which, when detonated, shatters the shell casing, producing thousands of high-velocity fragments and an accompanying sharply rising blast overpressure. More rarely, others are used to release [[chemical weapons|chemical]] or [[biological weapons|biological]] agents, either on impact or when over the target area; designing an appropriate [[Fuse (explosives)|fuse]] is a difficult task that lies outside the realm of terminal ballistics.

Other large-caliber projectiles use bomblets (sub-munitions), which are released by the carrier projectile at a required height or time above their target. For US artillery ammunition, these projectiles are called [[Dual-Purpose Improved Conventional Munition]] (DPICM), a 155&nbsp;mm M864 DPICM projectile for example contains a total of 72 shaped-charge fragmentation bomblets. The use of multiple bomblets over a single HE projectile allows for a denser and less wasteful fragmentation field to be produced. If a bomblet strikes an armored vehicle, there is also a chance that the shaped charge will (if used) penetrate and disable the vehicle. A negative factor in their use is that any bomblets that fail to function go on to litter the battlefield in a highly sensitive and lethal state, causing casualties long after the cessation of conflict. International conventions tend to forbid or restrict the use of this type of projectile.

Some anti-armor projectiles use what is known as a [[shaped charge]] to defeat their target. Shaped charges have been used ever since it was discovered that a block of high explosives with letters engraved in it created perfect impressions of those letters when detonated against a piece of metal. A shaped charge is an explosive charge with a hollow lined cavity at one end and a detonator at the other. They operate by the detonating high explosive collapsing the (often copper) liner into itself. Some of the collapsing liners go on to form a constantly stretching jet of material traveling at hypersonic speed. When detonated at the correct standoff to the armor, the jet violently forces its way through the target's armor.

Contrary to popular belief, the jet of a copper-lined shaped charge is not molten, although it is heated to about 500&nbsp;°C. This misconception is due to the metal's fluid-like behavior, which is caused by the massive pressures produced during the detonation of the explosive causing the metal to flow plastically. When used in the anti-tank role, a projectile that uses a shaped-charge warhead is known by the acronym [[High-explosive anti-tank|HEAT]] (high-explosive anti-tank).

Shaped charges can be defended against by the use of [[reactive armour|explosive reactive armor]] (ERA), or complex [[composite armour|composite armor]] arrays. ERA uses a high explosive sandwiched between two, relatively thin, (normally) metallic plates. The explosive is detonated when struck by the shaped charge's jet, the detonating explosive sandwich forces the two plates apart, lowering the jets’ penetration by interfering with, and disrupting it. A disadvantage of using ERA is that each plate can protect against a single strike, and the resulting explosion can be extremely dangerous to nearby personnel and lightly armored structures.{{Citation needed|date=March 2010}}

Tank fired HEAT projectiles are slowly being replaced for the attack of heavy armor by so-called [[Kinetic energy penetrator|"kinetic energy" penetrators]]. It is the most primitive (in-shape) projectiles that are hardest to defend against. A KE penetrator requires an enormous thickness of steel, or a complex armor array to protect against. They also produce a much larger diameter hole in comparison to a shaped charge and hence produce a far more extensive behind armor effect. KE penetrators are most effective when constructed of a dense tough material that is formed into a long, narrow, arrow/dart like projectile.

Tungsten and [[depleted uranium]] alloys are often used as the penetrator material. The length of the penetrator is limited by the ability of the penetrator to withstand launch forces whilst in the bore and shear forces along its length at impact.{{Citation needed|date=March 2010}}