M-240 mortar
In November 1953, the 240mm M-240 mortar was seen in public for the first time, it was towed by an armoured tracked carrier and caused great expectation in the West. It was an impressive weapon that was designed at the end of World War II, but due to the rush with which it was developed, unfortunately it was fraught with problems. Due to its huge size, this mortar lost all the advantages of this kind of weapons, such as the high mobility, easy handling and high rate of fire. Perhaps, because of this, only about 300 units were built, which cannot be considered a success for an artillery piece within the Soviet Army.
M-240 mortar gallery and more info