Composition B

M107 projectiles. All are labelled to indicate a filling of "Comp B" and have fuzes fitted

A 40 lb (18 kg) shaped charge munition (marked to indicate a Composition B filling) used for various demolition purposes such as boring a hole for a cratering charge

Composition B, colloquially "Comp B", is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades and various other munitions. It was also used for the explosive lenses in the first implosion-type nuclear weapons developed by the United States.

Ingredients

The standard proportions of ingredients (by weight) are 59.5% RDX (detonation velocity of 8,750 m/s) and 39.4% TNT (detonation velocity of 6,900 m/s), phlegmatized with 1% paraffin wax. Most commonly it is described as 60/40 RDX/TNT with 1% wax added.

Properties

• Density: 1.65 g/cm³
• Velocity of detonation: 8,050 m/s

Use

Composition B was extremely common in United States and other western nations' munitions and was the standard explosive filler from early World War II 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, which has a higher proportion of RDX (up to 75%).

Modern TNT-free alternatives

IMX-101 is slowly replacing Comp B in the US military.

See also

• Composition C
• Cyclotol
• RE factor