let’s mount a 150mm cannon on the tiniest tank chassis we have, what could go wrong

Due to its cramped interior and the large size of the ammunition required for the gun, only three spare rounds were transported in the vehicle. This would limit the effectiveness of the sIG 33 auf Pz. I if the supporting ammunition carriers could not reach them for whatever reason.

The weight of the 15 cm gun and the additional armor plates was simply too much for the weak Panzer I tank’s chassis. This overloading often resulted in many transmission and suspension breakdowns.

The main gun recoil during fire was so strong that the vehicle would wildly shake and could be thrown back.

The high profile was a big problem for the sIG 33 auf Pz. I too, making it an easy target for enemy artillery gunners.