German armour

Panzerkampfwagen IV Ausf F2, Panzer Grenadier Division "Grossdeutschland", Eastern Front, Summer of 1942.

In March of 1942, next variant Ausf F2 was produced, followed by Ausf G in May. Current research shows that in reality designation Ausf F2 was not used when describing Ausf F armed with 75mm L/43 gun and instead tanks known as Ausf F2 were in fact early Ausf G tanks. Ausf F2 and Ausf G variants were based on the long version PzKpfw IV chassis and were armed with newer 75mm KwK 40 L/43 gun (that was able to compete with Soviet T-34s armed with 76.2mm gun). When encountered in North Africa, British nicknamed Ausf F2 (early Ausf G) - "Mark IV Special", since it was superior to any American or British tank at the time. The installation of the new gun increased the overall weight of the tank and reduced its speed. Both Ausf F(F1) and Ausf F2 were identical except for their armament. Ausf F2's new 75mm L/43 gun was mounted with single baffle muzzle brake.
https://www-d0.fnal.gov/~turcot/Armour/pz3.htm