One of the main problems in tank building from the very appearance of this area of technology was the gas contamination of the fighting compartment. Time passed, new tanks, engines, guns and other systems appeared. But there was no dramatic improvement in conditions in the fighting compartment. Of course, the cannon ejectors and good old fans that appeared at the beginning of the second half of the 20th century improved the working conditions of the crew, but they could not fundamentally change the situation.
A significant improvement in the situation in the fighting compartment could be achieved only by two methods: either to make it fully automated and uninhabited, or to take the gun out of the internal volume of the tank. It was the second idea that was developed and embodied in metal by the engineers of the design bureau of the Sverdlovsk plant "Uraltransmash". In the 70s, in the department of special equipment of this design bureau under the leadership of designer N. S. Tupitsyn was developing a new self-propelled artillery installation "Object 237". The purpose of the work was to create a new self-propelled gun, which would first supplement the 2S3 "Akatsia" ACS in the troops, and then completely replace it.
As an experimental weapon for the new self-propelled gun mount, the 152-mm 2A36 gun mounted on the Hyacinth-S self-propelled guns and the 2A33 gun of the same caliber were chosen. The dimensions, weight and recoil of both guns required a new chassis. The basis for it was the corresponding unit of the T-72 tank. The normal operation of the large-caliber gun was supposed to be ensured by a new layout of the road wheels. They were still mounted six per side, but now the front three rollers and the rear three were closer together. Also, the large recoil of the 152-mm gun forced the engineers to significantly rework the suspension of the armored vehicle. Nevertheless, all the modifications to the chassis of the T-72 tank, although significant, were still less noticeable than the method of installing the gun.
Sverdlovsk engineers for the first time in Soviet practice carried the breech of the gun outside the fighting compartment. In a constructive sense, it looked like this. A special tower of a special shape was placed in the native seat of the T-72 tank turret. For the form, the designers nicknamed it the washer. This "washer" could be rotated 360 ° in the horizontal plane. Inside the original turret, the automatic equipment for feeding shells and casings was located, as well as the workplaces of the gunner and commander of the self-propelled gun. Of particular interest is the cannon mounting system. In order not to place the breech inside the fighting compartment and at the same time preserve the possibility of vertical guidance at significant angles, the axis of the lifting mechanism was placed almost at the very rear of the breech. As a result, it turned out to provide the new self-propelled gun with good aiming angles: circular horizontally and about 30 ° vertically.
The 2A33 and 2A36 cannons were completely isolated from the crew and the Object 327 self-propelled gun became the first domestic type of armored vehicle, in which, by definition, there was no problem of ventilation of the habitable volume. In addition, the free space inside the vehicle has increased: with the classic installation of the 2A33 cannon inside the fighting compartment, its breech would occupy about 70-75% of the total volume of the tower. As if not wanting to "pamper" the crew, the engineers of Uraltransmash installed an automatic ammunition supply and mechanized stowage in the vacant space. Separate loading shots were automatically removed from the stowage, fed up to the gun, and automatically sent to the chamber. For aiming when firing direct fire, the designers under the leadership of Tupitsyn have developed a new sight of their own design. It differed from previous types of similar equipment by its "sharpening" for use with a gun mounted to the top of the tower.
In general, "Object 327" was a very, very interesting project. Perhaps, having gone into series, he could have changed the appearance of self-propelled gun mounts around the world. However, as always, there were some problems. Most of the inconvenience was caused by the original location of the gun. Due to the high point of application of the recoil force, in some cases the machine could shake, if not even overturn. Because of this, confident fire was only possible in relatively small sectors in front and behind the vehicle. Of course, if necessary, the turn can be carried out with the help of tracks, but in this case the turning tower becomes fundamentally useless. The second problem of the "Object 327" lay in the need to load the gun at high elevation angles. The new mechanization of the projectile supply and the automatic loader often did not work properly, which led to delays in firing. Moreover, in the absence of a solution to this problem, the malfunction of the feed and loading mechanic could lead to the fact that the crew would have to get out from under the armor protection and pull out the jammed projectile or sleeve with their own hands. Finally, the lack of any protection for the breech of the gun, located outside the armored hull, was in doubt. Engineers considered the possibility of installing a special armored box, but it was not installed on prototypes.
Both prototypes of the "Object 327" had problems with automatic loading. One of them was equipped with the "Hyacinth" gun, the second - 2A33. In both cases, there were problems with the lifting of ammunition and their ramming. Tests of two self-propelled guns showed all the advantages and disadvantages of the applied method of installing the guns and gave hope for a successful completion of the project. Nevertheless, as of the beginning of the eighties self-propelled gun "327" still had a number of problems. Despite all the efforts of the design bureau employees and workers of Uraltransmash, it was not possible to achieve stable operation of all mechanics. In principle, it was possible to continue working and still bring the automation to mind. But Tupicin and his comrades no longer had time. The development of the special equipment department was literally stepped on the heels of another promising ACS. In the same design bureau of the Uraltransmash plant, under the leadership of Yu. V. Tomashov, the 2S19 Msta-S self-propelled gun was already in full swing. The much more familiar design of the 2C19 led to the fact that of the two projects - the original, but problematic and "banal", but simple in production - the second was chosen.
In the mid-eighties, the "Object 327" project was finally closed. Over the years since then, one of the prototypes of the self-propelled guns, presumably, has been disposed of. The second copy, carrying the 2A36 cannon, was sent to the Uraltransmash museum in 2004 after a long stay at the test site. The idea of an armored vehicle with a gun suspended above the manned compartment is still considered original and promising. Nevertheless, to this day, not a single such self-propelled gun has been able to reach large-scale mass production.
