A barrel and a barrel extension for being coupled to a firearm. The barrel extension can be threadedly engaged with a proximal end of the barrel. A chamber of the firearm can extend in at least the proximal end of the barrel. One or more channels can be formed in the exterior surface of the proximal end of the barrel and/or the interior surface of the barrel extension for providing fluid communication from the chamber to the forward end of the barrel extension between the barrel extension and the proximal end of the barrel for venting high pressure gases that may develop in the chamber.