I was just informed by lemegacool that Maruzen M11 mags (propane / green gas) work in this gun. He got one and it works, apparently producing a higher velocity than CO2. He said his gun chronies at 320 with CO2, and 350 with propane. My gun chronies at 350 with CO2, so not sure what that discrepancy is. But regardless, they work.
The mags are a bit more expensive through eHobby Asia, but in the long term, you'll be saving a small fortune on gas over the higher cost of CO2 powerlets.
And as an added bonus, the Maruzen mags look better and don't have that big knob on the bottom for screwing in the CO2 powerlet.