COMMON NAME – Composition A-3 (A-4)
FOREIGN NAMES – Hexogene/cire d’abrille (France), Füllpulver Nr 91-H5, Nr 92-H10, Nr H10.3 & NrH3 (Germany), Angayaku, Kosbitsu, Oshitsuyaku or Shouyaku Kosbitsu (Japan), Flegmatizirovannyi gheksoghen (Russia)
TYPE – High explosive mixture
DATE FIRST USED AS AN EXPLOSIVE – 1944
COUNTRY OF ORIGIN – Great Britain/USA
COMPOSITION – 91% RDX, 09% Paraffin Wax desensitizer
MOLECULAR FORMULA – CH6N602 (RDX) + CH3(CH2)11N6O2 (Wax)
MOLECULAR WEIGHT – 227
DENSITY – 1.63 g per ml pressed at 82,740 kPa (12,000 psi)
NORMAL STATE – Granular prills
PHYSICAL APPEARANCE/COLOR – White to buff in color, foreign countries may dye the materials such as Blue (Germany) and Red (Italy)
INITIATION – Minimum detonating charge of 0.25 g Lead azide, 0.22 g Mercury fulminate
SENSITIVITY – Insensitive to shock and friction, no explosions when struck with 7.62mm (.30 cal) rifle bullet
STABILITY – Stable in storage, should not be stored at temps above 75o C (167o F.) as wax will soften
DETONATION VELOCITY – 8,200 m/s (26,903 fps)
RE FACTOR (BRISANCE) [TNT=1.0] – 1.22
TOXICITY – No marked toxic effects
MELTING POINT – 200o C.(392o F.)
IGNITION POINT – 250o C.(482 o F.) Decomposes
SOLUBILITY – Insoluble in water, soluble in benzene or acetone
APPLICATIONS – PRINCIPLE USES – Press-loaded as a bursting charge in projectile
The Composition A series of explosives was originally developed in Great Britain during World War II. It was another attempt to utilize the power of RDX explosive and deal with the sensitivity of the crystals to detonation. The British formulation for Composition A was 91% RDX combined with 9% Beeswax. This powerful explosive mixture could be press-loaded into ammunition as a bursting charge. The American standardization of the Composition A mixture replaced the beeswax used by the British with a synthetic wax and resulted in Composition A-2. Later changes in the granulation of the RDX and in the method of mixing in the wax resulted in Composition A-3. The Composition A-3 explosive mixture has been used as the bursting charge in 20mm, 37mm and 40mm explosive ordnance. Composition A-4 explosive has an increased amount of RDX in the mixture. The mix of Composition A-4 is 97% RDX and 3% Desensitizer. The material is still able to be press loaded and is used as the explosive component of the Mark 211, Mod 0 .50 caliber cartridge.
