The high efficiency of the use of self-propelled 152-mm guns during the Great Patriotic War made this type of equipment one of the most promising. In the eyes of some specialists and military self-propelled guns with large-caliber guns, they have become a universal miracle weapon. Therefore, after the end of the war, work in this direction was continued. Among other production and design organizations, the topic of large-caliber guns for self-propelled guns was dealt with in the design bureau of Plant No. 172 (Perm).
In the middle of 1954, the designers of the 172nd plant completed engineering work on the M-64 cannon project. This 152-mm gun sent an armor-piercing projectile at a target at a speed of about 740 meters per second. At the same time, the range of a direct shot at a target with a height of two meters was equal to 900 m. As for the maximum range of a shot, at an optimal elevation, the M-64 threw a projectile at 13 kilometers. The project of such a weapon interested the military, and in March 55, Plant No. 172 was tasked with preparing all the documentation for the new gun, assembling a prototype, and also assembling a self-propelled gun armed with an M-64.
December of the same year was set as the deadline for assembling a prototype of the Object 268 self-propelled gun. The chassis of the T-10 tank was taken as the basis for the vehicle. Accordingly, all units remain the same. Object 268 was equipped with a V-12-5 diesel engine with 12 cylinders arranged in a V-shape. The maximum diesel power was 700 horsepower. The engine power was transmitted to a planetary gearbox with a turning mechanism of the "ZK" system. The transmission provided eight forward gears and two reverse. The fine-link caterpillar passed to the "Object 268" without changes, as well as seven road wheels on each side and three supporting rollers. Hull armor ranged from 50 mm (stern) to 120 mm (forehead).
Instead of the native turret of the T-10 tank, an armored wheelhouse was installed on the chassis. The welded structure of flat trapezoidal sheets had a solid thickness at that time. So, the frontal slab of the cabin had a thickness of 187 millimeters. The board was almost two times thinner - 100 millimeters, and the stern sheet was made only 50 mm thick. It should be noted that only the forehead, sides and the roof of the wheelhouse were connected by welding. Since the "Object 268" was conceived exclusively as an experienced self-propelled artillery installation, it was decided to fasten the middle part of the aft deck plate with bolts. Thanks to this, if necessary, it was possible to quickly dismantle the plate and gain access to the interior of the cabin and to the gun as well. First of all, this was necessary for the possible replacement of an experienced weapon.
The large caliber of the M-64 cannon forced the engineers to foresee a number of structural nuances. So, to reduce the length of the recoil - a very important parameter for self-propelled guns - the gun was equipped with a two-chamber muzzle brake. In addition, advanced hydraulic recoil devices were used. For the convenience of the crew, the gun had a tray-type chambering mechanism. Also, the M-64 became one of the first Soviet cannons to be equipped with an ejector. Thanks to this "build-up" on the gun barrel, it was possible to significantly reduce the gas contamination of the fighting compartment after firing. The combat stowage of the "Object 268" housed 35 separate loading rounds. With the M-64 cannon, it was possible to use the entire available range of 152 mm ammunition. The gun mounting system made it possible to aim within 6 ° from the horizontal axis and from -5 ° to + 15 ° in the vertical plane. For direct fire, the Object 268 had a TSh-2A sight. Since the designers and the military initially assumed the use of this ACS for firing from closed positions, in addition to the TSh-2A, a ZIS-3 sight was mounted. The tank commander also had at his disposal a TKD-09 rangefinder-stereoscopic tube, located on the rotary commander's tower directly in front of the hatch.
Additional self-propelled armament included one KPV anti-aircraft machine gun of 14.5 mm caliber. It was located on the roof of the wheelhouse and had an ammunition capacity of 500 rounds. In the future, the crew of a self-propelled gun of four could also receive weapons for self-defense, for example, Kalashnikov assault rifles and grenades. In addition, the issue of installing a coaxial machine gun with a cannon on the "Object 268" was considered, but the features of the combat use of this class of armored vehicles did not allow this to be done.
A combat vehicle with a combat weight of fifty tons and a 152 mm caliber gun was ready at the beginning of 1956 and soon went to the training ground. The updated fighting compartment and new armament had almost no effect on the driving performance of the T-10 chassis. The maximum speed reached during the tests was 48 kilometers per hour, and one diesel refueling was enough to overcome up to 350 kilometers on the highway. It is easy to calculate the specific fuel consumption: the self-propelled gun had five tanks. Three internal ones had a capacity of 185 liters (two rear) and 90 liters (one front). In addition, on the rear of the wings, the designers of Plant No. 172 installed another 150-liter tank each. In total, about 200-220 liters of fuel for every hundred kilometers. When traveling over rough terrain, the speed and power reserve, as well as fuel consumption, changed significantly for the worse.
During the experimental firing "Object 268" fully confirmed the design characteristics of the M-64 cannon. The range, accuracy and accuracy of this gun were much better than those of the ML-20 howitzer-gun installed on the ISU-152 self-propelled gun during the Great Patriotic War. First of all, the barrel length affected the characteristics. At the same time, the new M-64 cannon had a number of "childhood diseases" that were just beginning to be eliminated.
By the time the lengthy tests of Object 268 ended, American tank builders had created the M60 tank. The English Chieftain was soon ready. These armored vehicles had very good weapons for their time and no less solid protection. According to the estimates of the Soviet military and scientists, "Object 268", having met in battle with new foreign tanks, was no longer a guaranteed winner. Moreover, by the time a sufficient number of new self-propelled guns were produced abroad, even more advanced tanks could have appeared, which the Object 268 could no longer fight. Therefore, at the very end of the fifties, the "268" project was closed and all plans for the serial production of new ACS were canceled. The only collected copy was then sent to the Tank Museum in Kubinka.
Object 268 will appear in World of Tanks soon
