Abstract: Apparatus and methods relate to barrel arrangements for use with paintball guns. The barrel arrangement includes an insert that may be tubular and selectable by a user to have an inside bore diameter to provide desired fit with a paintball. An external barrel receives the insert and is attachable to a frame of the paintball gun. An externally mounted resilient band around an outside circumference of the external barrel facilitates centering and retention of the insert within the external barrel. Specifically, the external barrel includes a set of apertures through which extensions on an inside surface of the resilient band protrude into biasing contact with an outside surface of the insert.

Abstract: Apparatus and methods relate to gas regulators for use with paintball guns. The gas regulator includes a poppet housing interchangeable by a user to modify output pressure of the gas regulator. The poppet housing includes markings visible externally on the gas regulator indicating to the user the output pressure provided. The gas regulator may further include a rotatable adapter for coupling with a paintball gun. A regulator piston that functions to control the output pressure based on the poppet housing selected acts in some embodiments on an internal balanced piston for selectively opening and closing flow through the gas regulator.