Show/Hide Toolbars

Ordnance, Explosives, and Related Items

Navigation: Ordnance > Bombs > United States

US Bomb, 4000 lb LC, AN-M56, AN-M56A1

Scroll Prev Top Next More


This bomb is intended for use against targets of large area such as villages, towns, and cities to produce a tremendous blast effect. It is familiarly termed a blockbuster.

The body consists of a nose forging, three rolled plate sections, and a forged base plate. The nose forging is welded to the first plate section, and the three plate sections are welded longitudinally and circumferentially. The female base plate is threaded to the tail section of the body. The side walls have a minimum thickness of 0.3 inch and a maximum thickness of 0.5 inch. Suspension is provided by two lugs welded to the case 30 inches apart (15 inches on either side of the center of gravity). The normal box type tail is modified on this bomb by eight additional strut rods to give increased stability for this large bomb.

The 4,000 pound LC Bomb AN-M56A1 differs in that provision is made for a hoisting lug to be added at the center of gravity between the suspension lugs and also for two other suspension lugs to be screwed into the bomb body, 22 1/2° removed, for suspension in British planes.

Any future production will have inert nose and tail surrounds.

Hazardous Components

The standard filling for this bomb at present is cast TNT (3362 lb, 1528.2 kg), but some bombs in the future will be loaded with Tritonal. A full length Auxiliary Booster M111 is employed to insure complete detonation.

Other possible fillers include Amatol (3245 lb, 1475 kg) or Amatol 50/50 (3238 lb, 1471.8 kg)

See Also

Adapter Booster, M102, M102A1

AN Series Bombs

Booster, Auxiliary, M111

Nose, Impact, M103

Tail, Impact, M102

Tail, Impact, M162


OP 1664, Volume 2 - US Explosive Ordnance (1947)

USNBD - Bombs and Fuzes, Pyrotechnics (1945)

TM 9-1904, Ammunition Inspection Guide (1944)