GKO No. 4851 dated December 27, 1943, issued an order to “Design, manufacture and test of a new prototype gun for tanks and self-propelled guns” and detailed a study of the German 88mm KwK 43. GAU issued Design Bureau No. 9 with a proposal to develop the new powerful anti-tank gun, similar to the German 88mm KwK 43, with a shell velocity of at least 900 m/s.
A redesigned 85mm D-5T gun was developed and received the index D-5T-85BM, where BM stands for high power. The new weapon had a longer barrel, which allowed for a longer 85mm ammunition to be used, where the extra charge would give the projectile a velocity of 920 to 950 m/s. The gun could also use regular 85mm ammunition if needed.
The tank Object 244 was developed at the Factory Nº 100 under the leadership of A. S. Ermolaev at the end of 1943. In February 1944, the D-5T-85BM was manufactured and installed on an Object 237, IS-1, receiving the designation Object 244 or IS-3. his was the first-ever use of the designation IS-3 but had nothing to do with the later Object 703, also known as IS-3. gThe installation of the new gun didn’t entail any alterations to the tank since all the dimensions remained the same.
The muzzle velocity of the D5BM was 118 m/s more than the D5, almost 15.9% more up 950 m/s, which at a range of 500m could penetrate up to 131 mm of vertical armour, Almost 16% more when compared with the D5. Another big advantage was, despite the increase in ballistics, the cartridge size by extension of the ammunition load remains the same. The increase of 0,5kg in weigh was negligible, this would allow crews to maintain the same rate of fire, giving the D5BM yet another great advantage compared with the German 88mm KwK 43.
The gun was installed on a regular IS-85 turret, together with a coaxial 7.62mm DT machine gun. In addition to the regular sight, an experimental PT-8 articulated telescopic sigh with four-fold magnification with electric heating was made especially for this tank. Manufactured at Factory Nº 69, it was installed for aimed shooting from a twin mount. Instead of the PT-4 periscope sight, an MK-4 viewing periscope device was installed on the roof of the turret. The angles of vertical guidance were only of -3° and 15°, which was considered insufficient for more complete use of the combat capabilities of the main gun. The installation of two other DT machine guns didn’t differ from the regular installation on an Object 237 tank. Armour protection of the tank was the same as of the Object 237, except for the installation of a movable gun shield, similar to the experimental tank Object 240.
Together with the new gun, it was decided to install experimental units and assemblies of a new engine and transmission to be tested with the tank. A horseshoe-shaped steel plate radiator, a gearbox with synchronizers in 3-4 and 7-8 gears, making it possible to reduce the time for their switching and made it easier to control the vehicle, new rotation mechanisms with forced lubrification on the bearings and new fuel gauge. The chassis, electrical equipment and communications equipment remained the same in relation to Object 237.
At the end of March 1944, tests were interrupted at the Gorokhovets Artillery Research and testing Ground for the vehicle Object 244. The rapid wear of the new D-5T-85BM barrel meant the gun could be damage quickly, making it unsuitable for use. Besides, it was decided that new heavy tanks should be equipped with a 100mm or higher calibre gun.
In August 1944, the vehicle was put into test again until the end of October. This time, the vehicle was equipped with a new suspension system, without any returning rollers, the new design was made by Design Bureau Nº100 and was intended to be used on a new experimental tank: Object 252. The new suspension allowed for an additional load of up to 8 tons more. During the tests, the 85mm D-5T-85BM gun was replaced by a 122mm D-30 gun. The diameter of the double-track wheels was increased to 750mm compared with the standard wheels of the IS-1 tank. During the tests, the average speed of the tank was 22.5 km/h, and the maximum speed was of 35.4 km/h. The new suspension design was found to be satisfactory.
Object 244 was never used in combat, neither saw mass production. After the final tests, the vehicle fate is unknown, but likely to have been scrapped. Nonetheless, Object 244 will always be the original IS-3.