Projectile, 155 mm: Illumination, M118 Series

storage, transport and handling. The hollow shell interior contains an expulsion (ejection) charge, a canister assembly and a parachute assembly. In operation a nose-mounted MTSQ M501 series fuze functions (ideally at a height above ground of around 640 m), igniting the 53.5 g expulsion charge, contained in a tube running from the fuze, to a perforated baffle plate positioned on top of the canister assembly. The charge creates internal pressure which enables the canister assembly to rupture the shear and twist pins in the base and drive off the base plug. The canister assembly is then ejected from the base. The expulsion charge also ignites the 1.95 kg of illuminating compound inside the canister via a small 'first-fire' charge. It should be noted that Charge 1 cannot normally be used with the longer barrelled weapons. The Propelling Charge M4A2 is a white bag charge using 5.897 kg of M1 propellant divided into a base charge and four increments for firing as Charges 3 to 7. The increments are tied together by four cloth straps. 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) and the base igniter contains black powder. The Propelling Charge M4 is a white bag charge differing from the M4A1 as it consists of a base charge and two increments only for firing as Charges 5 to 7. The M2 flash reducer pad is used with this charge. The M3 and M4 series of charges are fired using the MK2A4 or M82 primer.