Abstract: A gas-powered gun for firing balls has a bolt slidable within a breech section to advance a ball to a firing position. A hammer is slidable in a first chamber formed in the gun body and a coil spring biases the hammer to a forward position for firing the gun. A sear member is movably mounted in the gun body and can hold the hammer in a rear, cocked position until the trigger is pulled. The gun has a pressurized gas circuit which includes a regulator capable of providing gas at a pressure not exceeding 300 psi. A second chamber formed in the gun body has an inlet connected to the regulator. A gas valve includes a valve body fixably mounted in the gun body between the first and second chambers. A valve stem is slidably mounted in a central passage of the valve body. The valve includes an elongate valve guide connected to the valve stem and having a valve seal mounted on a seat section formed on a rear end of the valve guide.