A ball launcher of the type that includes a piston slidable in a launch tube to increase air pressure behind a ball loaded into a front end of the launcher includes a launch tube of an outwardly flared construction to a diameter greater than the diameter of the ball loaded into the launcher. The outwardly flared end has an inwardly directed peripheral ledge defining an aperture smaller than the ball diameter. A spring located within the flared end biases the loaded ball against the ledge to create and maintain a pneumatic seal between the ball and ledge prior to launch.