CO2 guns for airsoft tends to shoot too hot for games, thats why you mainly see us using propane and green gas in our GBBs. But if you have your heart set on using CO2, try airguns though most but not all are non-blowback.
"Hey I'm the first one to say its a great country but its a straaaaange culture. This is a place where gun store owners are given a list of stolen credit cards but not a list of CRIMINALS and MANIACS. And now they're thinking of banning toy guns...AND THEY'RE GONNA KEEP THE F**KING REAL ONES!"
-George Carlin 1937 - 2008 (RIP buddy)