Composition B, colloquially "comp B", is an explosive consisting of castable mixtures of RDX

RDX

RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

 and TNT. It is used as the main explosive filling in artillery

Artillery

Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 projectile

Shell (projectile)

A shell is a payload-carrying projectile, which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot . Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used...

s, rocket

Rocket

A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...

s, land mine

Land mine

A land mine is usually a weight-triggered explosive device which is intended to damage a target—either human or inanimate—by means of a blast and/or fragment impact....

s, hand grenades, sticky bombs  and various other munitions. It was also used for the explosive lens

Explosive lens

An explosive lens—as used, for example, in nuclear weapons—is a highly specialized explosive charge, a special type of a shaped charge. In general, it is a device composed of several explosive charges that are shaped in such a way as to change the shape of the detonation wave passing through it,...

es in the first implosion-type nuclear weapon

Nuclear weapon

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

s developed by the United States.

Ingredients

The standard ratio of ingredients (by weight) is 59.5% RDX (detonation velocity of 8,750 m/s) and 39.4% TNT (detonation velocity of 6,900 m/s), together with an additional 1% paraffin wax to improve handling qualities. Most commonly it is described as 60/40 RDX/TNT with 1% wax added.

Use

Composition B was extremely common in United States and other western nations'

Western world

The Western world, also known as the West and the Occident , is a term referring to the countries of Western Europe , the countries of the Americas, as well all countries of Northern and Central Europe, Australia and New Zealand...

 munitions and was the standard explosive filler from early World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 until the early 1950s, when less sensitive explosives began to replace it in many weapons systems. Some NATO-approved munitions suppliers such as Mecar have continued to use Composition B in their products.

Composition B is related to Cyclotol

Cyclotol

Cyclotol is an explosive consisting of castable mixtures of RDX and TNT.It is related to the more common Composition B, which is roughly 60% RDX and 40% TNT; various compositions of Cyclotol contain from 65% to 80% RDX....

, which has a higher proportion of RDX (up to 75%).