- Years of issue – 1951 – 1958
- In total, 329 units were produced.
- Caliber – 240 mm
- Weight in firing position – 4150 kg
- Barrel length – 5000 mm
- Calculation – 11 people
- Travel speed – up to 40 km / h
- Rate of fire – 1 rds / min
- The greatest firing range – 9650 m
- Direct shot range – 800 m
- Shooting angles:
- Horizontal – 78 °
- Vertical + 45 ° + 80 °
The success of the 160-mm divisional mortar MT-13 designed by I.G. Teverovsky, forced GAU in January 1944 to develop tactical and technical requirements for the creation of a new 240-mm reinforcement mortar. The first mortar of this kind was designed back in 1942 at the Design Bureau of Plant No. 92 (Gorky) under the leadership of V.G. Grabin. He received the index “ZIS-27”, and after Grabin moved to the city of Kaliningrad, Moscow region, in TsAKB in 1943, he created another 240-mm mortar “S-16”. However, the real leader in this work was the 240-mm mortar, created in 1944-1945 at the Special Design Bureau of Smoothbore Artillery (Kolomna) under the leadership of B.I. Shavyrina. It was a further development of the M-160 160-mm divisional mortar of the 1949 model of the year. After the completion of all tests in 1949, this mortar was adopted by the Soviet army in 1950 under the designation “240 mm M-240 mortar”.
The M-240 mortar was a rigid (without recoil devices) breech-loading smooth-bore system mounted on a wheeled carriage. It consisted of: a barrel with a bolt, a breech, a frame with a shock absorber, a machine with aiming mechanisms and a balancing mechanism, a wheel travel with suspension, an arrow with a mechanism for transferring the mortar to a combat and stowed position, a base plate, a bolt paw and sighting devices.
The barrel was a smooth-bore pipe fixed in a trunnion clip, which allowed it to be tilted into the loading position and then returned to the firing position. The closure of the barrel from the breech was carried out by a bolt hinged upward. The breech was used to lock the barrel and transfer the recoil force when fired to the base plate. The conical part of the breech ended with a ball heel, with which the breech was connected to the bowl of the base plate. The machine consisted of two frames (upper and lower) of a stamped-welded structure, hingedly connected to each other.The lower frame was assembled on a two-wheeled combat axle. For vertical guidance of the mortar, the lifting and balancing mechanisms mounted between the brackets of the combat axle and the upper frame of the machine, combined into one lifting and balancing structure, served. The guidance mechanisms gave the barrel elevation angles from 45 to 80 ° and made it possible to conduct horizontal shelling at the highest elevation angle of 78 °. Shooting at an elevation angle of 45 ° was allowed after shrinking shots and only from hard ground. The lifting mechanism is screw type. A spring-type balancing mechanism was located on the right side of the machine. Initially, the mortar had a panoramic MP-46 sight, and since 1955, the M-240 mortar was equipped with an upgraded mortar sight with a K-1 gun collimator.
The M-240 mortar ammunition included only high-explosive steel mines (weighing 130.7 kg). The mine was equipped with a head fuse, which has two installations: for high-explosive and fragmentation action. For firing the M-240 mortar, five charges were used, designed for a firing range from 800 to 9650 m. Mines were brought to the mortar using a special cart. The rate of fire for the M-240 mortar was relatively low – 1 rds / min, which is explained by the laborious loading process. The mortar was loaded from the breech, for which the barrel was brought to a horizontal position. After opening the shutter, a tray was hung on the shutter wedge axle. Five people of the calculation manually lifted the mine, put it on the tray and sent the mine into the barrel bore. Then the barrel was lowered into the breech to fire a shot.
The time for transferring the M-240 from the traveling position to the combat position (at a pre-prepared firing position) was 20 – 25 minutes. The mortar was transported behind an ATL tractor or other artillery tractor at a speed of up to 40 km / h. Serial production of M-240 mortars was mastered in 1951 at the plant number 75 (Yurga).
In total, from 1951 to 1958, 329 M-240 mortars were manufactured. In the late 1960s, a self-propelled version of the 240-mm self-propelled mortar 2S4 “Tulip” was developed on the basis of the 240-mm M-240 mortar, which was adopted by the Soviet army in 1971. This mortar is still in service with the Russian army.