Since the rifle became the main weapon of the army, the loading method of the rifle has been greatly improved, thus increasing the shooting speed. However, the firing speed of firearms still cannot meet the needs of war. In order to improve the firing speed of firearms, many countries developed multi-barrel firearms before 1950s. The single-barrel hand-cranked machine gun invented by Englishman Pucher was patented in Britain in 17 18. However, because the gun body is too heavy and difficult to load, it has not attracted widespread attention. Some countries try to arrange many barrels in parallel or in a circle for volley or continuous shooting.
1862, American R·J· gatling invented the hand-held machine gun. There are six barrels with the caliber of 14.7 mm on the gun rack. The shooter turned the crank and six barrels fired in turn, which solved the problem of firing rate. In intense combat, 300 to 350 bullets can be fired every minute. The gun was patented in 1862, which played a great role in the American Civil War from 186 1 to 1865.