ISU-152 model 1945 The ISU-152 (Russian: Самоходная установка на базе танка ИС с орудием калибра 152мм, ИСУ-152, romanized: Samokhodnaya Ustanovka na baze tanka IS s orudiyem kalibra 152mm, meaning "IS tank based self-propelled installation with 152mm caliber gun") is a Soviet self-propelled gun developed and used during World War II.

It was unofficially nicknamed Zveroboy (Russian: Зверобой; "beast killer")[1] in response to several large German tanks and guns coming into service, including Tigers and Panthers.

On 6 November 1943 an order was issued for adoption of the improved variant, under the ISU-152 (ИСУ-152) designation, and in December production began at the Chelyabinsk Kirovsk Plant, replacing the SU-152.

It was intended these assault guns would be armed with a 152.4 mm gun-howitzer and used for penetration of the enemy defence in the offensive operations planned for 1942–1943.

Post-war ISU-152 modernisation included installation of night vision sights, replacing of the V-2IS engine with the V-54K, the 12.7mm machine gun was replaced by a newer variant, the ammunition capacity increased to 30 rounds, additional armor, automotive improvements and significant increase of the main fuel capacity.

During test firing at armour plates with different thicknesses, the ISU-152BM successfully penetrated a maximum of 203 millimetres (8.0 in) of RHA at 90° at ranges of up to 2,000 metres (2,187 yd).

However, during trials in July 1944, the gun showed some deficiencies, such as being difficult for the crew to operate, unreliability of the muzzle brake and the breech block, and unsatisfactory performance of the shells.

The secondary armament of the fighting vehicle consisted of two 12.7×108 mm DShK machine guns, one anti-aircraft and one co-axial.

In the area of the gun, where the mantlet combined with the hull front behind it and the housing of the recoil mechanism, the armour thickness was 320 millimetres (13 in).

However, the radical incline of the superstructure walls combined with the increased recoil of the gun, due to the lack of a muzzle brake, significantly complicated the work of the crew, and for this reason it was not adopted.

The ammunition capacity was increased to 30 rounds after the removal of an additional internal fuel tank placed in the crew compartment.

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 exposure and low mobility, or even a tank, with their smaller main guns.

To minimize the risks of being knocked out by Panzerfaust-equipped units during urban operations, the ISU-152 usually acted in one- or two-vehicle detachments alongside infantry squads for protection.

The ISU-152's heavy-calibre DShK machine gun was also useful for targeting Panzerfaust gunners hiding on upper floors of city buildings or behind protective cover and defensive barricades.

The sheer weight of the 152.4 mm shells resulted in an extremely low rate of fire, only two to three rounds per minute, and were not as accurate at long range as high-velocity tank and anti-tank guns.

However, the massive blast effect from the heavy high-explosive warhead was capable of blowing the turret completely off a Tiger tank.

While the low-velocity 152mm high-explosive shell did not generally penetrate heavy armor, it frequently killed or severely wounded the crew through spalling (splintering) inside the hull as well as injuries caused by blast concussion.

As a howitzer the ML-20S exchanged velocity and accuracy for throw weight and distance, and was not intended to compete with true anti-tank guns.

The ISU-152's 90 mm of sloped frontal armor, in contrast to the SU-152's 65 mm, provided excellent frontal protection from the 75mm KwK 40 gun of the ubiquitous Panzer IV and StuG family at all but the closest ranges, while also forcing the original Tiger I, with its vaunted 88 mm KwK 36 gun, to close to medium ranges in order to successfully penetrate the vehicle, negating its traditional long-range superiority and putting it within effective range of the Soviet T-34-85 medium tanks.

It had a very low rate of fire compared with specialised tank destroyers such as the German Jagdpanther or the Soviet SU-100, which could manage a brief burst of five to eight rounds per minute.

However, prior to the introduction of the SU-100 it was the only Soviet armored vehicle capable of tackling the German heavy tanks with any kind of reliability, and its ability to satisfy multiple roles meant it was produced in far greater numbers than the SU-100.

The ISU-152 was also sometimes used as self-propelled artillery for support on the battlefield and preparatory bombardments, though it had a medium range of fire and a slow speed of reloading.

Replenishing the vehicle's ammunition supply took over 40 minutes and required a very strong loader, due to the large size and weight of the shells - over 40 kg (88 lb).

To compensate it was simpler to concentrate the fire of several vehicles onto the target, sacrificing accuracy for volume of firepower.

For several decades it was the heaviest armoured vehicle in the Czechoslovak People's Army, which used these to test newly developed anti-tank obstacles.

In 1946, members of the Yugoslav 2nd Tank Brigade's first battalion, led by technical officer Stojimir Ilijevic – Guerrilla, recovered the self-propelled gun after five days of work.

[13] In 1955, the Soviet Army moved out from Dalian in northeastern China, officially ending 10 years of military occupation.

All weapons and armaments left behind by the Soviet Union were sold to the Chinese People's Liberation Army, including 67 ISU-152s; 45 were given to the newly created 1st Mechanized Division of the PLA.