“The 5 cm Pak 38 (L/60) (5 cm Panzerabwehrkanone 38 (L/60)) was a German anti-tank gun of 50 mm calibre. It was developed in 1938 by Rheinmetall-Borsig AG as a successor to the 37 mm Pak 36, and was in turn followed by the 75 mm Pak 40.
The Pak 38 was first used by the German forces during the Second World War in April 1941. When the Germans faced Soviet tanks in 1941 during Operation Barbarossa, the Pak 38 was one of the few early guns capable of penetrating the 45 mm (1.8 in) armor of the T-34.
The gun was also equipped with Panzergranate 40 APCR shots with a hard tungsten core, in an attempt to penetrate the armor of the heavier KV-1tank. The Pak 38 was also used in the Atlantic Wall because of its range and anti-tank capabilities, which would have been very useful in destroying allied tanks on the shore.
Although it was replaced by more powerful weapons, it remained a potent and useful weapon and remained in service with the Wehrmacht until the end of the war.
The Pak 38 carriage was also used for the 7.5 cm Pak 97/38 and the 7.5 cm Pak 50(f) guns.”Wiki