The Soviet Union in the 1920s was the most difficult period, in terms of weapons and equipment basically inherited the old equipment left by Russia, the long border and various fortresses, bases only a small number of heavy artillery defense, into the 30s because of the achievements in industrial construction, so a series of heavy artillery development programs were launched, which included both the modification of existing artillery, as well as the development of new artillery, artillery including 256, 305, 356 and other calibers.
An important factor affecting the development of large-caliber artillery is the railway heavy artillery defense concept put forward in the late 20s, for the Soviet Union at that time to deploy enough artillery in all military heavy places is obviously impossible, the enemy can find many breakthroughs in the long border line, the use of high mobility of railway artillery can achieve rapid mobile deployment of heavy artillery, with large corps combat.
In the early 1930s, the Soviet Union through the salvage of naval guns for repair and other methods to create some large-caliber train guns, and experiments proved that this idea has practical value, the Soviet Union on the one hand intends to use the preparation of the Soviet-class battleship 406 mm main gun to modify the train gun, on the other hand, the 450, 475 and 500 mm heavy guns to explore, through the analysis that the 450 mm class heavy guns have better ballistic performance, but the 500 mm class heavy guns are obviously the best damage ability, the Soviet Union chose the latter, This is the TG-1 500 mm caliber heavy howitzer.
The design of the gun was carried out by the OKB-172, which had experience in the development of large-caliber artillery. The TG-1, like other train guns, requires a whole train of carriages to form a combat system, which consists of 16 carriages with different functions, of which 3 are loaded with artillery, 6 are loaded with ammunition, and the others are powered cars, electric cars, spare cars, etc.
The TG-1 howitzer uses a 500 mm caliber, the entire length of the barrel is 13858 mm, the barrel weight alone reaches 85100 kg, the Soviet designers equipped it with two kinds of shells weighing about 2 tons, one is a high-explosive shell with a charge of 1450 kg, and the other is a concrete armor-piercing shell with less charge, which can penetrate 4.4 meters of thick concrete at an angle of incidence of 70 °.
For example, concrete armor-piercing shells have 4 types of propellants, corresponding to 340, 380, 430 and 490 m/s, and the maximum range is 19500 meters, while the high explosive shell has 6 kinds of propellant, corresponding to the initial velocity of 390, 430, 450, 540 and 600 m/s, with a maximum range of nearly 25 km.
This data difference on the one hand is the difference in ammunition characteristics, on the other hand is the two different ways of combat, concrete armor-piercing shell in order to achieve a "top attack" attack on the bunker, it needs a curved trajectory like a mortar, so the initial speed of the muzzle is not so high, and the high-explosive shell has a greater demand for range, as long as it can successfully hit the target and explode, as for what angle hit has no matter.
Such a bulky artillery naturally lacks flexibility, and the plan has two purposes, one is to install on a permanent concrete base as a fortress heavy artillery, and the other is to install on the train gun system, the gun has a pitch range of 15 ° ~ 70 °, and only a fine adjustment range of 3 ° left and right in the horizontal direction.
When using artillery, it is necessary to maneuver the entire train to the battlefield, because of the problem of shooting angle, it needs to build a railway in the direction of the battlefield, and then expand the artillery to shoot, the spare carriage of the train gun system has spare rails and other materials, which can temporarily build or repair about 40 meters long rails for combat needs, and each ammunition compartment can transport 24 shells. Although the deployment process is complicated and time-consuming, the train gun system composed of TG-1 howitzers has the ability to fight independently.
The TG-1 howitzer was planned to be built in 1942 as a special artillery unit of the high command department, and its role was similar to that of the German Gustav heavy train gun in World War II, but the Soviet design and construction progress was behind schedule, and only part of the structure, including the gun mount, was completed when World War II broke out, and the entire research and development work was suspended after the outbreak of the Great Patriotic War.
Although the TG-1 howitzer is significantly weaker than the Gustav heavy train gun equipped by the German army in terms of caliber and power, the two are similar in nature, both are directly subordinate to the high-level military department "big killer", TG-1 is like a scaled-down version of Gustav, in contrast to its use to be slightly more flexible, unfortunately it was not ready before the outbreak of war, otherwise it may play some role in the early defensive war.