A barrel porting system for a firearm in one embodiment includes a barrel defining an axially extending barrel bore, a porting device coupled to the barrel and including a plurality of gas portholes in fluid communication with the barrel bore, and an outer shroud encircling at least the porting device. The shroud includes at least one gas discharge port arranged to vent combustion gas from firing the firearm in an outwards direction. An annular gas collection plenum formed between the shroud and porting device is configured to collect gas from the gas portholes and discharge the gas through the at least one discharge port in the shroud. In one implementation, the plenum is formed by a recessed channel in the muzzle device which extends around the entire circumference of the device. Various threaded and unthreaded coupling methods may be used to secure the muzzle device to the barrel.