High Quality Content by WIKIPEDIA articles! The SU-122 (SU-122 stands for Samokhodnaya Ustanovka 122 mm) was a Soviet self-propelled howitzer used during World War II. The number "122" in the designation represents the caliber of the main armament a 122 mm M-30S howitzer. The Soviet High Command became interested in assault guns following the success of German Sturmgeschutz III SPGs. Assault guns had some advantages over tanks. The lack of a turret made them cheaper to produce. They could be built with a larger fighting compartment and could be fitted with bigger and more powerful weapons on a given chassis. However, assault guns could only aim their weapons by turning the entire vehicle, and were thus less suited for close combat than tanks.