https://www.planetminecraft.com/project/1-5-1-scale-m1955-d-20-52-p-546-howitzer/


The 152 mm gun-howitzer M1955, also known as the D-20, (Russian: 152-мм пушка-гаубица Д-20 обр. 1955 г.) is a manually loaded, towed 152 mm artillery piece, manufactured in the Soviet Union during the 1950s. It was first observed by the west in 1955, at which time it was designated the M1955. Its GRAU index is 52-P-546

152 mm has been a Russian calibre since World War I, when Britain supplied 6 inch Howitzers and Russia purchased 152 mm guns from Schneider (probably derived from the 155 mm Gun Mle 1877/16) for the Imperial Army. The new gun-howitzer, was a replacement of the pre-war ML-20 gun-howitzer (the 152 mm howitzer M1937) and various World War II era 152 mm field howitzers, Model 09/30, Model 1910/30, Model 1938 M10 and Model 1943 D-1. By Soviet definition, a 152 mm howitzer is 'medium'-calibre artillery. It was designated a 'gun-howitzer' because its muzzle velocity exceeded 600 m/s, and its barrel length exceeded 30 calibres. It equipped battalions in the motor rifle division artillery regiment and army level artillery brigades.

taken from,
https://en.wikipedia.org/wiki/152_mm_towed_gun-howitzer_M1955_(D-20)