73 mm ammunition for 2A28 gun

cent Wax). The rocket motor employed on both projectiles weighs 1.56 kg and is 380 mm long, containing 460 g of NDSI-2K propellant. In both cases the rocket motor is ignited after firing by a VPZ-9M pyrotechnic delay weighing 35 g. Once the projectile leaves the muzzle it is stabilised by six spring-loaded forward-folding fins. On target, the shaped warhead is initiated by a VP-9 piezoelectric point impact fuze via an igniter in the base of the shaped charge. The PG-15 warhead can penetrate 300 mm of armour while the PG-15N can penetrate 400 mm. The charge used to propel projectiles from the 2A28 barrel is the 4BN34 (also written as BN34) contained in a steel cartridge case 102 mm long and weighing 875 g; the case alone weighs 390 g. The rimmed stub case (flange diameter 83 mm with mouth internal diameter 63 mm) is crimped onto the projectile tail and contains a perforated disc which creates a high/low-pressure situation to impart a low-pressure impulse to launch the projectile and initiate the VPZ-9M pyrotechnic delay train for the rocket motor. The case is made of BW 11 steel. By contrast, the basic 73 mm FRAG-HE rounds, a later development, do not have a rocket motor. There are two basic types of FRAG-HE round, the OG-15V and OG-15VM, differing only in the weight and type of explosive in the 309 mm long cast-iron warhead on the projectile. The OG-15 FRAG-HE projectile warhead used with the OG-15V round contains 753 g of TNT while the OG-15M projectile used with the OG-15VM round contains 655 g of TD-50 (TNT/dinitronaphthalene).