With the space taken up by the main gun, the crew and the engines, there was surprisingly little room in a tank for the ammunition which was vital to survival on the battlefield. Most tanks could hold enough shells for around ninety shots, tightly packed into every conceivable space. Most commanders favoured a mix of 40 per cent high explosive and 60 per cent armour piercing, but it was often a matter of a personal assessment of the likeliest target to be faced on a given mission. Getting the balance right was a crucial decision. Armour piercing rounds were useless against infantry and high explosive would not penetrate tank armour. Having a large stock of the wrong kind of ammunition effectively left the tank impotent.
In battle, many experienced crews could fire one round every five seconds, so not surprisingly, ammunition supplies could quickly become exhausted, rendering the tank helpless. At this delicate juncture, the tank commander was faced with a crucial choice: either leave the field to re-arm and re-fuel, or await re-supply in the field.
The bulky tank ammunition could not be transported on foot and required a vehicle to re-supply the tanks. Trucks were too vulnerable to be sent into the fighting area, so the Germans developed a special turretless tank called a Munition-schlepper to carry out the dangerous job of ammunition re-supply on the battlefield.
To ensure that ammunition supplies were used wisely. German tanks were forbidden from firing on the move. The prescribed tactic was to strictly engage enemy targets from a static position. This made aiming much easier giving the gunner the best chance as he lined up his target on the middle triangle of his gun sight. To help him in aiming his shells, they were equipped with a tracer element, which produced a trail of bright light to help pinpoint the path of the shell as it flew towards its target.