Ballistic performance of the rifle-fired Mills No. 36 Grenade: some unreal numbers, some real numbers and some statistics

Data from WWI sources claimed for the range and accuracy of the Mills No. 36 Grenade fired from a cup-discharger attached to a Lee-Enfield rifle have been scrutinised. Statistical analysis shows that range data has generally been rounded to the nearest 10 yards, possibly to reduce the memory burden on the front-line soldier; these data are accordingly labelled as ‘unreal.’ Accuracy data appear to have not been manipulated and are regarded as ‘real’ numbers. Poor accuracy, both absolute and relative to projectiles launched from rifled-barrels, is attributable to the cup-discharger acting as a smooth-bore mortar. The internal and external asymmetry of the No. 36 grenade meant that it could never be an inherently accurate weapon. It has been shown that the average windage between the gas-check disc and cup-discharger was probably about 0.015-inch.