The 20mm Hispano round generates about 4 times more recoil when fired from 20 kg rifle, compared to .50BMG (12.7x99mm) round, fired from 10kg rifle (such as Barrett M95). To make the recoil more or less bearable by the average shooter, the Croatian designers developed a quite interesting counter-recoil system, that uses a reactive principle. The system consist of the large reactive tube, located above the barrel. The forward end of this tube is connected to the barrel at about its middle point. The rear part of the tube forms the reactive nozzle. When gun is fired, some hot powder gases are fed from the barrel to the reactive tube and back, forming a back-blast with reactive force that cats again the recoil forces. The large muzzle brake further helps to decrease the recoil. This reactive system, once popular in large caliber (about 80 - 100 mm and bigger) recoilless rifles, almost never had been used in such relatively small weapons.