SU-12 / SU-1-12 / GAZ-AAA

The first full-fledged artillery units of self-propelled type were created in the USSR in the early-1930s but were built in single copies or in small series. With the adoption of the "system of tank-tractor and auto-armor armament of the Red Army" (Workers 'and Peasants' Red Army) in 1929, the direction of developing ACS on the automobile chassis sharply accelerated. At that time, the task was to develop a universal artillery installation to combat the enemy's manpower, armored vehicles and aircraft. But such a gun could not be developed.

Only by the end of 1932, the leadership of the Red Army abandoned this concept of universality, and by the middle of 1933 the technical task was issued to the Leningrad Kirov Plant, which in a short time had completed all the work on creating the ACS. Tests of self-propelled artillery installation took place in the early autumn of 1933 and showed good results. After the tests, the SAU was adopted by the Red Army under the designation SU-12. Therefore, the Red Army's need for mobile artillery systems had to be satisfied by installing a regimental cannon of the 1927 sample in a rotating wheelhouse on the GAZ-AAA truck platform.

In 1934 about 200 experimental models were built. Its based on GAZ-A but longer and has an extra pair of wheels. Its main purpose is to carry 76mm cannon. Because of hurry in designing the car had several problems. For example sometimes the brakes on the rear wheels got stuck, and the transmission whined.

The ACS SU-12 was an installation consisting of a cannon of a sample of 1927 of 76 mm caliber placed on the platform of GAZ-AAA or “Morland” trucks in a special rotating wheelhouse. A batch of the Moreland TX-6 truck (Morland) with a 6 × 4 wheel arrangement was purchased for the needs of the Red Army in America in the early 1930s.

A 76.2-mm regimental cannon of the 1927 model, which was produced in those times in the USSR in large quantities, was used as an artillery gun. Only the barrel and the recoil system were changed to reduce the recoil from 1000 mm to 500 mm. The gun was mounted on a rotating bollard. The fire could be fought from the spot, and on the go. However, the sector of horizontal shelling was limited: it was impossible to fire forward, because in this case, the powder gases damaged the cab of the truck.

The Cannon was mounted on the stand and in the marching position unfolded forward and fixed, and the rotating part of the cabinet was placed on the brake. The Self-propelled unit, designated by the SU-12, could fire both from the place and on the move. The Sector of its horizontal firing was 270 ° because of the impossibility of conducting the fire forward-powder gases damaged the cab of the machine.

A simple optical sight and a monocular artillery panorama were used to conduct aimed fire. Ammunition in the form of 36 shots was located in special boxes on the rear wall of the control booth of the ACS. The ammunition consisted of high-explosive fragmentation projectiles and shrapnel.

The first SAU SU-12 had no armored protection at all. The following ACS SU-1-12 had a U-shaped vertical protection and a small roof with armor plates 4 mm thick. Such body armor provided protection for the crew and equipment only from small arms bullets and small fragments. In the future, armor has become more complex form with an embrasure for the gun barrel, the placement of shields at an angle of 25 °, closing windows for sighting devices. On the trunk was attached additional shield mask 4 mm thick. The Front leaf of the felling had an opening for the swinging part of the gun and two windows on the left side — under the panorama Reflector and for the visor tube.

The Windows were covered with latches, and the main flap, fixed on the body of the cannon. To protect against powder gases, the rear wall of the car cab was reinforced with a 2 mm steel plate with a hole in the middle. The latter served to communicate with the driver and, if necessary, closed the inside of the cab with a steel damper. Two charging boxes were fastened To the steel reflector plate: Right for 18 regular grenades, left for 18 shrapnel.

From 1933 to 1935, 99 SAUs were produced, of which SU-12 - 48 cars, SU-1-12 - 51. In general, these self-propelled guns were manufactured as a palliative needed to train personnel and work out the interaction of self-propelled artillery with tanks (SU-12 was operated in mechanized brigades).

SU-12 turned out to be quite reliable, efficient and mobile self-propelled artillery. She successfully coped with the task of fire support of infantry and tanks, as well as the fight against the enemy infantry. The power of the 76.2-mm projectile was quite enough until 1942 to fight the enemy’s tanks, although it did not have such a task. The main criticism of the SAU SU-12 and SU-1-12 was that they received a weak armor protection and general vulnerability due to the automobile chassis.

By 1938, almost all the self - propelled guns SU-12 were decommissioned due to various failures. Only the ACS SU-1-12 on the GAZ-AAA chassis remained in the ranks . The ACS SU-1-12 took part in the battles on Lake Hassan in the summer of 1938, along the Khalkhin-Gol river in the summer of 1939 and in the Finnish Winter War of 1939-40. At the beginning of 1941, there were 3 SAU SU-1-12 in service , which were located in the Trans-Baikal Special Military District (ZabOVO).

The SU-12 Self-propelled unit has been built serially since 1933 and had been quite a mobile means of fire support of mechanized units. However the passability, reliability and security of it left much to be desired, and it allowed to make the only correct conclusion: self-propelled artillery installations should be released on crawler turn.

The army was deeply convinced that real self-propelled guns on tank chassis would very soon replace the Su-12. Repression, which affected the supreme command of the RKKA, in particular Marshal Tukhachevsky, the supporter of the SAU, caused the cessation of such works.