Abstract: An improved normally open (NO) gas pressure regulator is provided. Preferably, the regulator is employed with a paintball marker and operates as a NO regulator yet automatically purges the retained pressure downstream of the regulator upon removal of the supply pressure. The gas pressure regulator of the present invention includes a pressure-controlled plunger inside the NO regulator that allows the regulated downstream gases to be purged from the system as the supply source is removed from the marker. Accordingly, since the downstream regulated gases are allowed to exit the system when the supply source is removed, the regulated gas pressure is released and the paintball marker is rendered inoperable and safe.

Abstract: A paintball marker for firing a projectile includes a main body. The main body includes a breech and a feed port connected and a feed tube connected thereto. The main body is originally configured for launching a projectile having a first size. The invention includes a conversion kit to enable a marker to launch projectiles that are smaller than what can be originally launched. A breech insert is positioned within the breech, a feed insert is positioned within the feed port and a replacement barrel, with a smaller diameter bore, are provided to reduce the size of the all conduits within the marker for launching a projectile having a second size that smaller than the first size. The feed insert directly engages the breech adapter to prevent the movement of the breech adapter. Also, connection of the barrel secures the breech insert in place.