The D-20 152mm Gun-Howitzer was built shortly after the end of WWII by the F. Petrov Design Bureau in the Soviet Union and was first seen in public during the 1955 May Day parade in Red Square, Moscow. The D-20 is a very large gun, equating to 6-inch caliber, and is heavy for a simple towed carriage. Its restricted mobility, however, is somewhat compensated for by its range of 17,230 meters.The D-20, also known as the M1955 or M-55, was the newest 152-mm towed howitzer in the Soviet and Warsaw Pact inventory when first introduced in 1955, replacing the heavier, less powerful, 152-mm gun-howitzer ML-20 (M1937). It is organic to army/front-level artillery and to the artillery regiment/brigade of a tank or combined arms army, while the self-propelled version 2S3 is found in the artillery regiment organic to motorized rifle and tank divisions. The D-20 was exported to all Warsaw Pact armies (except Bulgaria). The Type-66 is a Chinese version, which has been exported to Iraq.
The D-20 uses the same carriage as the 122mm field gun D-74. This short split-trail carriage is distinguished by caster wheels (folded upward for travel) at the end of each trail; a prominent base plate connected to the bottom forward cradle; and a scalloped, winged shield with traveling central portion. The tube, however, differs from that of the D-74inthat it is much shorter (29 versus 47 cal), larger in diameter, and has a larger size double-baffle muzzle brake. Both guns have a two-cylinder recoil mechanism above the tube, and both tubes are prominently stepped, with a semi-automatic, vertically-sliding, wedge breech block. Both guns also fire similar case-type, variable-charge, separate-loading ammunition. The circular firing jack and caster wheels make it possible to rotate the whole gun swiftly through up to 360 degrees. It also has direct fire sights for both day and night and is capable of engaging armored targets with direct fire. It can be towed by truck or armored tractor (AT-L).
The D-20 was the first 152-mm cannon system to incorporate a semiautomatic vertical-sliding-wedge breech block. It fires FRAG-HE, OF-540 with a RGM-2 Fuze Model at a rate of 5-6 rounds per minute with a maximum firing range of 10 miles. Although the ammunition for the system was not changed, modifications allowed a slightly higher rate of fire to be achieved (6 rounds per minute rather than 4), although the sustained rate of fire was unchanged. Because the carriage is based on that of the 122-mm gun D-74, the D-20 cannot be elevated above 45°.
Specifications
Alternative Designations M1955 or M-55 Date of Introduction 1955 Proliferation At least 13 countries Description Crew 8 Carriage 122-mm gun D-74 Combat Weight (mt) 5.7 Chassis Length Overall (m) Travel Position 8.10 Firing Position 8.69 Height Overall (m) 2.52 Width Overall (m) Travel Position 2.35 Firing Position INA Towing Speed (km/h) Max Road 60 Max Off-Road 30 Max Cross-Country 15 Fording Depths (m) .5 Emplacement Time (min) 2.5 Displacement Time (min) 2.5 Prime Mover AT-S Tracked vehicle; MT-LB; Ural-375; Ural-4320 ARMAMENT Main Armament Caliber, Type, Name 152-mm, canon Barrel Length (cal) 25 Rate of Fire (rpm) Burst 5-6 Normal INA Sustained 1 (65 rounds the first hour) Loader Type Manual Breech Type Vertical sliding wedge Muzzle Brake Type Double flared Traverse (°) Left 29 Right 29 Total 58 Elevation (°) (-/+) -5/+45° FIRE CONTROL Indirect Fire PG-1M Panoramic Telescope (PANTEL) Direct Fire OP 4M Collimator K-1 Gun Display Unit None Fire Control Computer None VARIANTS None MAIN ARMAMENT AMMUNITION Caliber, Type, Name 152-mm Frag-HE, OF32 Indirect Fire Range (m) Minimum Range 4600 Maximum Range 17,400 Complete Projectile Weight (kg) 43.56 (OF25) Muzzle Velocity 655 m/s Fuze Type V-90 PD 152-mm, HEAT, BP-540 Direct Fire Range (m) Minimum Range 0 Maximum Range 1000 Armor Penetration (mm) INA Complete Projectile Weight (kg) 27.00 Muzzle Velocity 655 m/s Fuze Type GPV-3 PD 152-mm Frag-HE, OF-96 Indirect Fire Range (m) Minimum Range INA Maximum Range 24,400 Complete Projectile Weight (kg) 43.56 (OF-64) Muzzle Velocity INA Fuze Type PD Other Ammunition Types DPICM, DPICM-BB, Incendiary, Ex-pendable Jammer, Chemical, Flechette, Semi-active laser-guided Kras-nopol- M Frag-HE 
