A self-contained round of ammunition has a cartridge casing including a tubular body defining a cylindrical rifled bore and a base threadably attached to the casing body and forming a closure for a breech end of the rifled bore. A sabot which carries a ring airfoil projectile is constrained for limited axial movement within and relative to the bore from a loaded position adjacent the base to a fired position wherein an annular arresting lip integrally formed at the muzzle end of the cartridge body engages an annular abutment surface on the sabot. The lip defines a cylindrical muzzle opening having a diameter smaller than the diameter of the bore and larger than the major diameter of the projectile which may pass freely there through. The sabot in its loaded position cooperates with the base to form a pressure chamber therebetween for receiving gasses of explosion generated by a powder charge contained within the base and in communication with a primer mounted in the base. A bore engaging ring on the sabot has lands and grooves complementing associated portions of lands and grooves defining the rifling within the bore. When the round is fired the moving sabot is abruptly halted within the bore by the arresting lip at the muzzle end causing the spinning ring airfoil projectile to separate from the sabot and leave the cartridge along a flight path. A launcher for firing the self contained round includes a detent member which cooperates with a detent notch in the cartridge base to restrain the cartridge against angular movement about its axis and relative to the launcher when it is fired.