Patent ID: 7775148

Claim:
Projectile launcher barrel apparatus comprising: an inner barrel having an inner barrel chamber having proximal and distal ends; a projectile in the inner barrel chamber; an outer casing surrounding the inner barrel; an axial gas chamber surrounding the inner barrel between the inner barrel and the outer casing; plural spaced pressure-activated valves connected between the axial gas chamber and the inner barrel chamber, the valves sequentially opening from pressure behind the projectile and admitting pressurized gas from the axial gas chamber to the inner barrel chamber and accelerating the projectile through the inner barrel toward the distal end, wherein the pressure-activated valves have sealing seats and sliders on the seats, wherein the sliders have relatively large lifting areas and relatively small opposite retainer areas, wherein as the projectile passes the valves pressure within the inner cylinder chamber produces greater forces on the large areas, and pressure within the axial gas chamber produces lesser forces on the small retainer areas, and wherein force differential between the greater forces and the smaller forces move the sliders away from the seats, releasing pressure from the axial gas chamber to the inner barrel chamber behind the projectile.