After the successful combat debut of the M-13 rocket in the summer of 1941, the need for a larger rocket arose one year later.
This led to the introduction of the M-30 rocket with shorter range but larger payload.
The new rockets were initially launched from wooden frames called »Rama«, a Russian copy of the German »Wurfrahmen«, as the name indicates.
At the end of 1942, an improved version of the M-30 with longer range was introduced, called M-31, still launched from the »Rama«s.
In March 1944, at last, twelve M-31 in two rows were installed on the Studebaker US6 chassis, thus dramatically improving the mobility.
This combination proved extremely successful in the further course of war, in particular during the fierce street fightings of Budapest and Berlin.

Note
The vehicle shown here comes with the rear ground stabilizers installed and the twelve 300mm rockets loaded, in other words... it's ready to fire!