Projectile, 155 mm: DP, Improved Conventional

inside the ogive by a booster charge, below which is a pressure plate. The projectile base is occupied by a two-piece Base Bleed Base Burn (BB) unit filled with a barrel-shaped Hydroxyl Terminated PolyButadiene (HTPB) composite propellant grain, developed by Talley Defense Systems, to be ignited by propellant gases on firing. The inhibited HTPB burns slowly for approximately 22 seconds in such a manner that the resultant gases fill the vacuum created by the aerodynamic air flow behind the shell. This reduces drag behind the projectile, therefore enhancing range. In operation, the M577A1 time fuze functions at the selected instant during the projectile's trajectory and initiates the booster charge located at the base of the fuze well. This initiates the expulsion charge formed by 90.7 g of M10 propellant. A 96.4 g clean-burning igniter charge in a red cloth bag is sewn to the rear of the base section and an M2 flash reducer pad is assembled in front of the base charge. The complete charge is 533 mm long. The Propelling Charge M4A1 is similar to the M4A2 but does not contain the M2 flash reducer pad (although this can be added if required), the base igniter contains black powder. The Propelling Charge M119A1 is a white bag charge with an igniter pad at the base and a ring-shaped flash reducer pad located on the front of the bag; the forward end also contains lead foil as a decoppering agent. The M119A1 contains approximately 8.62 kg of cool-burning M6 propellant with a central igniter consisting of a moulded nitrocellulose tube containing benite strands. The Propelling Charge M119A2 uses a red charge bag and does not have a laced jacket. It is provided with an igniter protector cap and tie strap which must be removed before firing; the circular red cloth igniter pad weighs 113 g.