Those who prefer using CO2 for powering up their GBB-Rs (that is if they use the WE M4 GBB-R), can now place orders at Airsoft Buddy at a discounted introductory price. Cheaper to use CO2 so they say,  but at least more options on what type of magazines we can use for this M4 GBB-R... "Airsoft Buddy is accepting Pre-Order for WE Gas Blow Back M4 CO2 Magazine now. Pre-Order price is US$40@. After the pre-order period, the price will be US$45@."