|Engine Power (hp)||650|
|Speed Limit (km/h)||43|
|Standard Shell Penetration (mm)||208 - 282|
|Standard Shell Damage||345 - 575|
|Rate of Fire (rounds/min)||5.7|
This heavy SPG on the basis of the ISU-122S was developed in 1944, with a prototype built in October. The 130-mm S-26 gun, based on the B-13 naval gun, was mounted on the ISU-122S. The vehicle underwent automotive and firing trials by 1945, but penetration characteristics were inferior to those of the 122-mm guns, and the war was drawing to a close, so the vehicle never entered service.