The SU-122P is a Soviet tank destroyer or assault gun. It has a powerful gun but the reload is relatively long.
The production of the SU-100 has begun in the early spring of 1944, but the production rates was slowed down due to a lack of 100mm D-10S guns. By this time, the ChKZ produced the SU-85 SPG. However, a stronger tank destroyer was needed. Soon to be launch was a new series of self-propelled guns, known as the SU-122P, which was to replace the SU-100.
The SU-122P was a little different from the SU-100. Although both self-propelled guns were based on the T-34-85 chassis and shared the same fighting compartment and cabin, the SU-122P, as the name implies, was fitted with the 122-mm D-25S gun with a muzzle brake.
In September 1944, the self-propelled gun prototype was built and sent sent for trials. Despite the success, the order for mass production has not been approved. The main reason for dissatisfaction was that the D-10C gun was much better than the 122mm gun in terms of armor penetration and rate of fire, and even had a stronger impact. Mass production of SU-122P was not considered during the war or after. However, later a new ISU series of tank destroyers were designed. Among them was the ISU-122S, the successor of the SU-122P as it had the same gun. Also, the IS-2 shared the same chassis as the ISU-122 but had the new D-25T gun.