A pneumatic assembly for a paintball gun is provided. The pneumatic assembly includes a valve stem, and a bolt slidably mounted on the valve stem. The bolt includes at least one bolt port arranged through a sidewall of the bolt. A sealing member is provided on the valve stem in communication with an inner surface of the bolt. The bolt slides from a rearward position to a forward position along the valve stem. Compressed gas flows through the bolt port and through the bolt aperture to fire a projectile when the bolt is in the forward position. A paintball gun incorporating the pneumatic assembly is also provided.