155 mm M3A1 – The M3 series propelling charges

The full charge consists of approximately 5.50 pounds of propellant including a base charge and four unequal increment s loaded in cloth bags. The hags are fastened together with four cloth straps sewn to the base and tied on top of Increment 5. Charge M3 is assembled without flash reducer pads. Charge M3A1 includes 3 flash reducer pads containing potassium nitrate or potassium sulphate. A2 ounce pad is assembled forward of the base charge and there are two 1-ounce pads forward of Increments 4 and 5. The igniter charge of the M3A1 is 3.5 ounces of clean burning igniter (CBI) in a red cloth bag sewn to the rear of the base section. The igniter charge of the M3 is 3 ounces of black powder. The seams of the base charge section are inverted on the M3A1 only so that the edges of the cloth are inside to reduce residue after firing.