As Achmed would say...
Holy crap!
Not this thing... if you want to get a worthy gas-operated M4, stick to Western Arms. All AGM and Jing Gongs aren't worth half the money you'd pay for them. As well as GHK Kalasznikow (yes, that's the correct way to write it). Trust me, I've checked them all. The only cheaper option is WE. But it goes down easily anyway.