Matt takes the G&G Combat Machine M4 Gas Blowback Rifle outside for some test fires and explains how the Gas Blowback System was put inside an AEG body in this Evike.com video. He says the benefit of this as it allows you to convert it back to an AEG provided you have the G&G gearbox to drop into it. For the cold weather season, this GBB will be ready for you, as long as it's converted into an AEG.