SU-122 Self-propelled Gun
In April 1942 the Central Artillery Directorate (»GAU«) instructed several teams to begin work on a medium mechanized self-propelled vehicle capable of mounting the powerful 122mm gun.
The work of the Uralsky Heavy Machine Tool Factory (»UZTM«) and Zavod N°.592 was overseen by a special team from the Z.Kotin's Commissariat for Tank Production (»NKTP«).
UZTM based its »U-35« (subsequently known as the »SU-122«) vehicle on the chassis and hull of theT-34, placing the »M-30« 122mm gun in a fully armoured casemate with 45mm frontal armour.
The increased size of the crew compartment, in comparison to a turreted vehicle, allowed a crew of five (commander, gunner, driver, and two loaders) to operate the large gun with relative ease, with the crew placed as follows: driver's station at the left front hull, gunner's station at the left behind the driver, commander's station was at the right front and the two loaders (the M-30 loaded separately) were behind the howitzer's breech.
With an overall weight just over 30.5 tonnes (30 tons), the SU-122 had a road speed ot 55km/h (34mph) and with added fuel tanks, a range of 300km, making it more than capable of keeping up with the rapidly advancing Soviet tank forces of the 1943 late summer.
After receiving approval from the GKO, the first 25 SU-122 were completed still in December 1942.
SU-122's were used to form medium self-propelled artillery regiments.
These Medium SP regiments consisted of 16 SU-122's (organized in four batteries) and one commander's T-34 tank.
Soon, the new SU-122 became very popular due to it's quite powerful armament and good armor protection.
In May 1943, the new BP-460A HEAT (High Explosive Anti-Tank) round was accepted. That ammunition allowed the SU-122 to deal with enemy AFV's at long distances.
However, like with most Soviet self-propelled guns, its primary role was direct fire support ot infantry against enemy strongpoints.
Two attempts to improve the performance were undertaken at Uralmash, called »SU-122M« and »SU-122-3«.
The main improvement was the adoption of a new ball mount for the gun which improved its traverse and the vehicle's frontal protection.
The advent ot the more powerful »SU-152« self-propelled gun as well as the highly effective »SU-85« tank destroyer, however, led to the decision in November 1943 to discontinue production of the SU-122 just 11 months after the first of 638 vehicles had been produced.