Big Gun

THOMAS FLEMING’S ARTICLE “TANKS” (Winter 1995) was fascinating in recounting the U.S. Army’s more than sixty-year struggle to develop a truly world-class fighting vehicle, but a gap in the story is evident. The marvelousIy detailed cutaway illustration of the M1A1 Abrams tank, with more than thirty callouts for its components, fails to pick out the raison d’être for the two-million-dollar vehicle: its main weapon and ammunition.

That ungainly-looking cantilevered tube protruding over the port side of the tank is a marvel of the weaponeer’s art. It is a smooth-bore, very highpressure cannon, capable of firing routinely at pressures greater than 80,000 psi. Its predecessor, the M-60 tank, fired routinely at only 50,000 psi. That high-pressure capability was a direct outgrowth of the 120-mm Delta gun program of the 1960s at the Watervliet and Picatinny U.S. Army arsenals.

The business end of the entire system is the munition, which travels the three thousand meters to its target and delivers the killing blow. This too is a marvel of the weapon engineer’s art. The kinetic-energy penetrating shot is launched from the cannon at more than a mile a second after undergoing a launch acceleration of more than 75,000 g’s. Its construction and ability to penetrate armor are astonishing but probably still classified.

The history of these weapons developments has not been recounted in the open literature but probably should be. It is a model of applied technology.

Sidney S. Jacobson
Chester, N.J.
(The writer is a retired developer of antiarmor munitions at the Picatinny Arsenal.)