By the mid-fifties, the potential of missile weapons became obvious in the context of the fight against tanks, but anti-tank guns were still in no hurry to go into the past. Another attempt was made to create a promising anti-tank self-propelled artillery installation with a weapon of increased power. As part of the research work "Taran" was created ACS "Object 120" and 152-mm gun M-69 for it. In terms of their combat characteristics, both samples surpassed all developments of their time.
R&D "Battering ram"
In May 1957, several resolutions of the USSR Council of Ministers set a course for the development of armored vehicles to combat enemy tanks. The industry was tasked with developing several armored vehicles with guided missile weapons, as well as an artillery mount with a high-powered weapon. The creation of the ACS was carried out within the framework of the R&D "Taran".
According to the terms of reference, the new ACS was supposed to have a mass of no more than 30 tons and carry protection against shells of small and medium calibers. For a self-propelled gun, it was necessary to create a large-caliber gun weighing no more than 4.5 tons with a direct shot range at a tank-type target of 3 km. At this distance, the gun was supposed to penetrate 300 mm of homogeneous armor at an encounter angle of 30 °.
The head contractor for "Taran" was OKB-3 of the Sverdlovsk "Uralmashzavod", headed by GS Efimov. The design of the gun was entrusted to the Perm SKB-172 chief designer M. Yu. Tsirulnikova. The shots were created at the Moscow Research Institute-24 under the leadership of V. S. Krenev and V. V. Yavorsky. Several other organizations were involved in R&D as developers and suppliers of individual components and components.
Two guns
During the same 1957, a number of organizations led by SKB-172 were looking for the optimal shape of the weapon for the future ACS. Calculations have shown that the required ratio of fire characteristics and mass can have systems of caliber 130 and 152, 4 mm. By the end of the year, SKB-172 completed preliminary designs for two similar weapons. The product with a caliber of 130 mm received the working designation M-68. The 152 mm gun was designated M-69.
The M-68 project offered a 130-mm rifled gun with a barrel length of 10405 mm (80 calibers) for a separate-case loading shot. The estimated initial velocity of the projectile reached 1800 m / s. The mass of the gun on the installation was 3800 kg - 700 kg less than the maximum permissible according to the technical specifications. It was proposed to attack armored objects using a specially developed armor-piercing sub-caliber projectile weighing 9 kg. Its penetration characteristics corresponded to the wishes of the customer. Also provided for a high-explosive fragmentation projectile with a variable propellant charge.
In the M-69 project, a 152-mm gun with a smooth barrel of the same dimensions was worked out. The relative length of the barrel is 68, 5 calibers. The weight of the product has reached the maximum allowable 4500 kg. The estimated maximum speed of the projectile was 1700 m / s. Against tanks, the gun was supposed to use an 11, 5-kg armor-piercing sub-caliber projectile or cumulative ammunition. Fortifications and manpower could be attacked with a high-explosive fragmentation projectile.
In February 1958, at a meeting at the State Committee for Defense Technology, taking into account the research results, the terms of reference were changed. In particular, the range of a direct shot at a target with a height of 3 m was reduced to 2.5 km. Other requirements remain the same. Now the enterprises had to make and test two types of experimental guns.
Manufacturing and subsequent shooting of M-68 and M-69 products took about a year. Barrel groups were manufactured by plant # 172. Ammunition received from related enterprises. The tests were carried out at the site of the plant using the M36-BU-3 ballistic installation. During the test firing, it was possible to confirm the main tactical and technical characteristics of the guns.
In March 1959, a new meeting was held, at which the final appearance of the future ACS "Taran" or "Object 120" was determined. When choosing a weapon for self-propelled guns, the decisive factor was the range of ammunition. The 130-mm M-68 cannon could only hit tanks with a sub-caliber projectile, while the M-69 also had a cumulative ammunition. Due to the greater flexibility of application for further development and use on the "Taran", a smooth-bore 152-mm gun was recommended.
At the very beginning of the next 1960, Uralmashzavod received two experimental M-69 guns for installation on Object 120. Soon, the only prototype self-propelled gun with such weapons went to factory tests.
Technical features
The finished product M-69, used as part of the self-propelled gun "Taran" was a smooth-bore gun with a caliber of 152.4 mm with a barrel length of 9.045 m, using a separate-sleeve loading. The breech of the gun was equipped with a semi-automatic wedge breech. An ejector was placed near the muzzle. To partially compensate for the recoil, a slotted muzzle brake with 20 holes on each side was used.
The gun mount had hydropneumatic recoil devices with a resistance force of 47 tf. Due to the use of such devices and an effective muzzle brake, the maximum recoil length was only 300 mm.
Vertical guidance of the swinging part with the tool was carried out hydraulically or manually. The guidance angles are from -5 ° to + 15 °. The installation included a mechanism that, after each shot, automatically returned the barrel to the loading angle. The gun mount was located in a turret of circular rotation, which provided firing in any direction.
"Object 120" transported ammunition of 22 separate loading rounds. For a faster feed into the gun, shells and casings were placed in a drum stack. Due to this, the gun could execute 2 shots in 20 seconds.
Several rounds for different purposes were developed for the M-69. To combat manpower and fortifications, a 152-mm high-explosive fragmentation projectile weighing 43.5 kg with a propellant charge of 3.5 kg (reduced) or 10.7 kg (full) was intended. The fight against armored vehicles was provided with cumulative and sub-caliber shells weighing 11, 5 kg. Together with them, casings with 9, 8-kg charges were used.
The muzzle velocity of the sub-caliber projectile is 1710 m / s. The range of a direct shot at a target with a height of 2 m - 2.5 km. The pressure in the bore reached 4 thousand kgf / cm 2. Muzzle energy - more than 19, 65 MJ. The effective firing range reached several kilometers.
At a distance of 3.5 km, with a direct hit on the target, the projectile penetrated 295 mm of homogeneous armor. At a meeting angle of 60 °, the penetration was reduced to 150 mm. At a distance of 2 km, the gun could penetrate 340 mm (0 ° angle) or 167 mm (60 ° angle). At a distance of 1 km, the maximum tabular penetration value reached 370 mm.
Thus, the newest self-propelled guns "Object 120" with the M-69 cannon could successfully hit any existing armored vehicles of a potential enemy at ranges of up to several kilometers. It should be noted that according to some characteristics, the 152-mm gun from the early sixties can be compared with modern models.
However, there were some notable drawbacks. First of all, the mobility of the self-propelled gun suffered, since the large length of the barrel increased the overall size of the armored vehicle. Despite the aft placement of the fighting compartment, the muzzle of the barrel extended several meters outside the hull. When driving over rough terrain, this threatened to stick the trunk into the ground with unpleasant consequences.
End of "Battering Ram"
Tests of the Object 120 self-propelled guns with the M-69 cannon started at the beginning of 1960 and lasted only a few months. Already on May 30, the Council of Ministers decided to stop work on the "Ram" theme due to the expected obsolescence. At the same time, the industry received assignments to develop a new 125-mm tank gun with improved characteristics. The result of this project was the 2A26 / D-81 smoothbore gun. In parallel with it, new anti-tank missile systems were developed.
The no longer needed experimental "Object 120" was sent for storage. Later he got to the museum of armored vehicles in Kubinka, where everyone can see him now. This self-propelled gun immediately attracts attention with a long barrel hanging over the paths for visitors. Even without a muzzle brake, the M-69 cannon almost reaches the opposite row of armored vehicles.
With the closure of the R&D "Taran", work on 152-mm smooth-bore cannons for fighting tanks stopped for a long time. New projects of such weapons appeared only in the eighties, when it became necessary to increase the firepower of the main tanks. However, this direction has not yet yielded real results and has not influenced the rearmament of the troops.
The 152-mm M-69 smoothbore gun developed by SKB-172 was one of the most powerful guns of its time and could be guaranteed to solve the assigned tasks. However, even before the completion of the tests of its carrier, it was decided to abandon large calibers in favor of more compact systems. Nevertheless, the M-69 cannon and the Object 120 self-propelled guns during the tests were able to show the highest characteristics, thanks to which they took an important place in the history of domestic weapons and military equipment.
