Description
These are percussion primed cartridges containing fin stabilized, high explosive antitank (HEAT) projectiles. Each projectile incorporates a setback armed, M509A1 point initiating base detonating (PIBD) fuze which has a piezoelectric (Lucky) crystal in the point initiating element.
The projectile body is painted olive drab with yellow or black stenciled markings. The windshield is unpainted. The tail boom assembly is coated with clear lacquer (M348) or anodized black (M348A1). The cartridge case is unpainted. The cartridge case markings, lot number, year of manufacture, caliber, and designation, are stamped into the cartridge case base.
The M348 has a cone tube extension which is not present in the M348A1. The fin cross-section of the M348 is rectangular while that of the M348A1 is T-shaped.
Functioning
When the primer is struck by the firing pin of the weapon, the black powder is ignited through primer, retainer, and igniter to flash through the igniter perforations and ignite the propelling charge. Rapidly expanding gases from the burning propellant force the projectile through the gun barrel with a velocity of 2,800 feet per second. The obturator expands to prevent escape of gas pressure past the projectile while it is in the barrel, and the fins stabilize the projectile in flight. Upon impact with the target, distortion of the piezoelectric unit generates an electric current to initiate the fuze and detonate the explosive charge. As the copper cone is crushed, the detonation results in an intensely focused high velocity shock wave which causes failure of the target armor, and a jet of molten metal penetrates the target interior.
Hazardous Components
Filler - Composition B (1.56 lb, 0.71 kg)
Cartridge case - T27E2
Propelling charge - M6 (5 lb, 2.27 kg ); M1 (5.44 lb, 2.47 kg)
Primer - T69
Igniter, fin assembly - T33E2
Physical Data
Length, overall - 33.74 in, 857 mm
See Also
Cartridge, 90mm HEAT, M348 (T108E40)
Source(s)
TM 9-1300-203, Artillery Ammunition (1967)
