The KwK- designation denoted a vehicle-mounted cannon. Anti-tank guns were designated Pak-. The Pak-40 was the original 75-millimeter gun which the KwK-40 was derived from.

The use of the 88mm Flak 18 as an anti-tank gun predated the T-34 by many a year, having originally been used in a pinch by the Condor Legion during the Spanish Civil War, and subsequently during the Battle of France and the North African Campaign. While the Flak 18/36/37 and subsequent Pak 43 development could easily rip open a T-34, the terrible surprise for the Germans was that the Pak 36 and Pak 40 seemed only to hurt the T-34 when it was about to plow through their positions.