above. Also, some of them received an additional armour plate welded on the upper mantlet front. The modernisation was carried out in the Leningrad Kirov Plant. ISU-152M ISU-152M was the final variant of ISU-152, developed in 1959. The work was now transferred to the Chelyabinsk Kirovsk Plant. This modernisation was parallel to the IS-2M program and the ISU-152M used many elements of the tank. The factory designation was Object 241M (Объект 241М). The innovations included night vision sights, increased ammunition stowage for the 12.7 mm machine gun, which was replaced by the improved DShKM, and internal automotive improvements. It had the same new commander's cupola and sights as the ISU-152K. It also had the same main internal fuel tank capacity, , adding more to the vehicle′s range on a road compared to the ISU-152, and an increased ammunition capacity to 30 rounds due to the removal of an internal fuel tank. The gun had a maximum range of . The ring protecting the sight was present, and the armour of the upper mantlet front was further increased with a thicker additional armour plate. The ISU-152M had the same V-54K engine with a heater, but lacked the cooling system. Use The ISU-152 self-propelled gun combined three battle roles: heavy assault gun, heavy tank destroyer and heavy self-propelled artillery. The 152.4 mm gun used a number of powerful (shell and charge) ammunition. Some of these ammunition had a 43.56 kg high-explosive shell, or a 48.78 kg armour-piercing shell, or the heaviest of all, the 53-G-545 (53-Г-545) long-range concrete-piercing ammunition with a 56 kg shell. The ISU-152 was used for infantry and tank support in attacking fortified enemy positions in a direct-fire role, for artillery support on the battlefield in an indirect-fire role and for engagement against armored vehicles in a direct-fire role. Heavy assault gun As a heavy assault gun, the ISU-152 was an extremely valuable weapon in urban combat operations such as the Battle of Berlin, Budapest and Königsberg. The vehicle's excellent armour protection finally provided the 152.4 mm gun with good protection from most German anti-tank guns, allowing it to advance into the face of direct anti-tank fire, while the huge, low velocity, high-explosive rounds were excellent at blasting open even the most heavily fortified and reinforced enemy strongpoints. Such actions would be much more dangerous and much less effective for a conventional towed artillery piece, with their high crew