Nicknamed ‘The Bitch' (‘Suka’ in Russian) or ‘Golozhopii Ferdinant’ (‘Naked Ass Ferdinand’ after its profile’s similarity to the German Ferdinand), the Soviet Su-76 self-propelled gun was the second most produced armoured vehicle in the USSR during WWII, surpassed only by the T-34.
Armed with a 76.2mm ZiS-3 gun installed in an open compartment atop a lengthened T-70 chassis, the Su-76 was most successfully employed in an infantry support role, either as a light assault gun or providing indirect fire support.
In an AT role, its 76.2mm ZiS-3 gun could deal with most German tanks including the Panther and the Tiger (if hit in the right spots from a short distance). Its speed, light weight and low ground pressure allowed the Su-76 to move through terrains unsuitable to other armoured vehicles.
Like its German counterparts, the SU-76 main drawback was the lightly armoured open compartment (10 to 30 mm) which offered little to no protection against the enemy and the harsh weather conditions of the Eastern front, hence its poor reputation among the men who crewed it.
Close to 14,000 vehicles left the assembly lines between January 1943 and mid-1945. SU-76M continued to serve post-war and a few fought against the United Nations during the Korean War.
In this photo, Soviet infantry supported by Su-76M ‘attack’ German positions in East Prussia, said to be near Königsberg, spring of 1945.
Note: The SU-76 crew member’s relaxed stance points to the usual Soviet posed photo. Posed or not, it is, imo, representative of what a SU-76 in action would look like.