The artillery was called karl" because of the involvement of the artillery general karl baker in the development. The prototype was manufactured in 1939. The prototype has 8 pairs of road wheels, while the production model has 11 pairs. The "karl" gun uses two types of shells, the s be shell weighs 2. 17 tons, and the le be shell weighs 1. 70 tons. Cars 1-4 went to the front line with the 628th heavy artillery battalion in july 1941, and were later assigned to the 883th heavy artillery battalion. "