Before the advent of tactical missile systems in the Soviet Army, the question was urgently raised about the delivery of limited ammunition to the battlefield. In the middle of 1950-x it was decided to create a special self-propelled gun and mortars for the use of tactical nuclear weapons.
So, in November 1955 year began work on self-propelled mortar 2B1 "Oka" and self-propelled gun 2А3 "Condenser-2P".
The most successful mortar was. Moreover, the artillery part was engaged in Kolomna SLE mechanical engineering, and the chassis "object 273" - KB Kirovsky plant in Leningrad. 420-mm mortar was intended for the firing of nuclear ammunition weighing 750 kg at a distance up to 45 km.
As the main weapon used 420-mm smooth-bore mortar 2B2 installed on the base of the tank T-10. The length of the barrel was about 20 meters. The weight of the self-propelled person exceeded 55 tons. Due to the lack of non-slippery devices, when shot, the machine went back to 5 meters.
Charging the mine was carried out from the state part, which significantly increased the rate of fire, which was 1 shot in 5 minutes
In the original position self-propelled mortar was managed only by a mechanic driver-the rest of the calculation (6 persons) was carried on a truck or an armored carrier.
A total of four self-propelled installations 2B1 were built in the Kirov plant. 7 November 1957 in the Moscow Military Parade in Moscow "Oka" was first demonstrated to the international community along with the 406-mm self-propelled gun on the same chassis. The demonstration of these huge weapons caused a furor among foreign journalists and local inhabitants. Some foreign experts have expressed the opinion that they are shown on the Red Square of the artillery station - just a propaganda designed for a frightening effect. They were not far from the truth. During the mortgage test, firing ordinary ammunition was not able to withstand the laziness, tore the gearbox out of the mount, and there were other breakdowns.
The completion of the mortgage lasted until 1960 year, when the resolution of the Council of Ministers on the cessation of work on Oka and SM-54 gun came out. The main reason for this was the emergence of tactical uncontrolled missiles on a lightweight crawler chassis with better passability.