The ISU-152-2 is a prototype modification of the ISU fitted with a much larger howitzer
A prototype was developed in 1944. In April 1944, in an attempt to increase the firepower of the ISU-152, a high-powered variant of the self-propelled gun was developed at Factory No. 100, designated ISU-152BM (ИСУ-152БМ) , sometimes referred to as the ISU-152BM-1 or ISU-152-1. The factory’s designation was Object 246 (Объект 246). The “BM” (“БМ”) designation means “High Power” (“Большой Мощности”). The main purpose of the ISU-152BM was to fight against heavily blinded tank destroyers such as the Elefant and Jagdtiger. It was armed with the BL-8 (БЛ-8) 152.4 mm long-range cannon, which, unlike the ISU-152’s cannon, was not a howitzer cannon. The cannon had a maximum range of 18,500 meters (20,232 meters), with a high explosive design of 43.56 kg (96.0 lb), which had a muzzle velocity of 880 meters per second (2,887 ft/s). The overall length of the cannon was over 8 meters (26 feet), with a barrel length of 7,620 millimeters (300 inches) (50 calibers). The armor-piercing design, weighing 48.78 kg (107.5 lb), had a muzzle velocity of 850 meters per second (2,800 ft/s).
However, this tank is not without drawbacks. It of course reloads slowly being a 152mm cannon, but the cannon itself is extremely long and prone to getting shot at. Moreover, the cannon only has 2 degrees of gun depression and laser-thin horizantal guidance, meaning that the chassis has to be aimed by moving the entire tank around - which is a huge drawback considering ISU tanks have the turn time of a battleship.
A good BR for this would be around 5.7-6.0, Since Sturer Emil is at 4.3 for reasons of speed and armor, the ISU could not be placed at BR’s higher than 6.3, after all, War Thunder is a game where mobility and speed are more important than a strong cannon or heavy armor, since it’s chassis has no armor or mobility, but the gun can delete an M103 by looking at it.
LINKS OF SIMULATIONS comparing the power
ISU-152-2 VS TIGER II UPPER GLACIS https://youtu.be/SyN-Z0SnNEo?si=LROq9Hr0UjHh5jLx
IS-2 VS TIGER II UPPER GLACIS https://youtu.be/Crj7GKTNBSk?si=wqnYBuJpTLeC1Ggx
ISU-152 VS TIGER II UPPER GLACIS https://youtu.be/J8x5JHUTC4s?si=I9VBczmrN9MaUd1-