A projectile launching apparatus includes a bolt (for chambering a projectile) and a bolt valve with a gas passageway for communicating the gas from a chamber housing to a breech assembly. Gas received within the gas chamber is compressed by a piston and communicated through the breech assembly to a projectile. The compressed gas expands in the barrel, thereby propelling the projectile out of the barrel in a single stroke of the piston. The bolt may be returned to an initial position by a magnet and/or spring that is coupled to the valve, and the piston may be returned to an initial position by way of vacuum pressure. The bolt valve may also include a mechanical retention element such as a sear and a release pin. The sear may the bolt in a first position until the piston from the compressor has moved sufficiently to push the release pin.