In simplest terms, firing at extremely high rates of speed creates a tremendous amount of heat. Firing that many rounds through one single barrel would likely Heat it to the point of very likely melt or distort the metal. By using multiple barrels, that distributes the heat over a wider range and prolong the life of the weapon. Second, it’s a simplified mechanism that allows the gun to operate at a high rate of fire while at the same time reducing extreme movement of the firing mechanism that would otherwise be required.
Latest Answers