A pneumatic assembly for a projectile launching system includes a body defining a continuous bore. A nozzle is positioned within the bore adjacent a forward end and is moveable between a rearward position wherein the nozzle facilitates passage of a projectile through a projectile port and a forward position wherein the nozzle prevents passage of a projectile through the projectile port. The nozzle is biased to the forward position and configured for fluid actuation to the rearward position by activation of a first fluid control valve. A valve seat defines an accumulation chamber rearward of the nozzle. A firing valve member is moveable between a forward position wherein the firing valve member fluidly seals a passage through the valve seat and a rearward position wherein the passage is fluidly opened such that fluid in the accumulation chamber is free to flow through the passage and out of the nozzle.