After producing domestic howitzer H155 mm M65 based on the US M114 155 mm howitzer, Yugoslav People's Army was not satisfied with the maximum range of that gun and current artillery weapons at disposal. Decisions were made to start domestic production of new large caliber guns. In same time construction documentation of 152 mm towed gun-howitzer M1955 (D-20) with few D-20 guns was bought from the Soviet Union. Dissatisfied with a range of both US 155mm and Soviet 152mm gun and after analyzing both US 155mm and Soviet Union 152mm guns and considering the lack of desired features, a number of specifications were defined with characteristics that new domestic gun-howitzer should have: