Krupp Schrapnellgranate

Schrapnellgranate L/3,7. It was composed by : body with copper driving band, ogival head, three high explosive cases, central tube, bullets, colophan, diaphragm, bursting charge. It was equipped with a quadruple acting fuze. The cartridge was charged with nitro-glycerine powder and was equipped with a screw primer.

The body was made of steel and inside it looked like an ordinary shrapnel, except that the tube connecting the fuze with the base charge was placed on the left hand, whereas in the middle it had two cases containing the high explosive. Outside the copper driving band was pressed into a groove milled near the base. The steel ogival head, containing the fuze, was screwed into the body.

The high explosive, composed by 125 g of Trotyl, was shared in four distinct charges placed lengthways in the body of the shrapnel. The head charge (o₁) surrounded the primer (d), containing fine grain nitro-glycerine powder. The second charge (o₂) was contained in a thick-walled case (D), the third charge (o₃) in a thin-walled case (D’), and the last charge (o₄) was filled among the bullets placed in the middle of the body hollow. The bullets placed at the top and at the bottom were instead packed in the colophan.

The base charge (s) was composed by 70 g of powdered Trotyl and was connected with the time fuze (F) by means of a steel tube (T), parallel with the central charge. Its diameter was reduced so that the flame coming from the fuze was able to cause only the explosion and not also the detonation of the base charge. The shrapnel contained 294 hardened lead bullets, weighting 10 g and having a diameter of 12-13 mm. They were separated from the base charge by means of a steel diaphragm.

The special quadruple acting fuze was very similar to Ehrhardt fuze and worked in the same way : time or percussion fuze for shrapnel, percussion fuze with or without delay for H.E. shell. It was made of aluminium and inside was double-banked, the upper level containing the time mechanism (F) and the lower level the percussion mechanism (P). It was equipped both with a delay action mechanism and a safety device against the bursting into the bore.

Operation of the Schrapnellgranate. Firing with time fuze, the burst of the base charge (s) threw the bullets, the head and the two cases containing the explosive without detonating the four bursting charge. The case (D’) fell on the ground without effect, but the head prolonged its flight, keeping its straight trajectory thanks to the case (D), which acted as stabilizer. Hitting the ground or an obstacle, the percussion fuze (P) caused the burst of the charge (o₁) and (o₂).

Firing with percussion fuze, the charge (o₁) detonated, causing at first the detonation of the second charge (o₂), then the break of the two cases (D) and (D’), and subsequently the detonation of the charges (o₃) and (o₄). Finally the base charge (s) detonated and the different parts of the shell burst almost simultaneously.

With percussion fire, when the Schrapnellgranate burst, it produced on the average 79 splinters weighting more than 10 g. The fragmentation of the wall was quite uniform, since the charges were placed along the axis of the shell, the only exception being the upper part of the body where the head was screwed and the Trotyl among the bullets was replaced with the colophon. The angle of the cone of dispersion of the splinters was between 115°-120°. With time fire, in addition to the bullets, 50 splinters weighting more than 10 g fell on the target. The angle of spread of the bullets was almost the same of the ordinary shrapnel, 14°-15° at 1000°.

Universal shell

Ehrhardt

Krupp