Cartridge, 106 mm: HEAT, M344 and M344A1

two types of round. The projectile nose cone adaptor carries a threaded conical cap acting as an ogive with a piezoelectric element connected by a wire to initiate the PIBD M509A1 or M509A2 fuze in the base. An aluminium chamber threaded to the projectile base supports the PIBD fuze, six folding fins and a piston assembly used to open the fins after firing. As the projectile is fired it is propelled along the barrel. The same propelling pressure builds up inside the piston assembly, so as soon as the projectile leaves the gun muzzle the piston moves to the rear to extend the six tailfins providing in-flight stabilisation. On impact with a target the piezoelectric element generates an electrical charge to initiate the PIBD fuze and detonate the projectile charge. The resultant detonation produces a high-velocity particle jet to penetrate the target armour. The M344 round uses an M93 or M93B1 perforated steel cartridge case; the M344A1 uses an M94B1 case. All types of case have an M57 percussion primer press fitted in the base; the M57 consists of a perforated steel tube containing a black powder priming charge and a brass bead. The M344 has a propelling charge of 3.67 kg of M10 propellant while the M344A1 uses M26 double-base, multiperforated granular propellant. In both instances the charge is contained in a rayon and plastic liner. The maximum effective range of both types of round is approximately 1,350 m, although the maximum possible range can be as high as 3,000 m. Muzzle velocity is 503 m/s. The M344A1 warhead can penetrate 150 mm of armour set at an angle of 60º. The 106 mm HEAT, M344 (originally the T119E11) and M344A1 were developed for use against armoured targets. These two 106 mm (actual calibre 105 mm) rounds differ in several respects, the most obvious being the types of cartridge case and propellant employed.