The debate is over on the going "green in airsoft" as there exists the most environment friendly gas to power your gas blowback, and here's Jonathan Higgs of Airsoftology to tell you about the most effective way of taking out the OPFOR and your team mates in airsoft. By using the abundant Brown Gas that can come in different flavours if you have the guts to smell it... "Move over Green Gas! Airfarce Industries presents the newest way to power your Gas Blowback airsoft gun: Brown Gas.