Abstract: The barrel of a firearm is provided with side ports, on opposite sides, adjacent the muzzle. The positioning of the ports, longitudinally of the barrel, is determined according to the pressures of the explosion gases, and the acceleration of the projectile. The acceleration of the projectile occurs in response to, and during, the increase in volume of the explosion gases. This occurs only in a small portion of the length of the barrel, at the breech end, and after that position, the gases decrease in pressure. The recoil occurs after the projectile leaves the barrel and the gases leave the barrel. The side ports are adjacent the muzzle, in the region where the gases have decreased in pressure, and are dimensioned to let nearly all the gases escape by the time the projectile leaves the barrel; they are arranged diametrically opposite each other, and they cancel each other, and greatly reduce and nearly eliminate, the recoil.