Originally Posted by Hata
Just wonder, do I have to finish off whole CO2 canister before I can take it out? OR I can take it out even I haven't finished the whole canister?
I worry the canister will fly off once I unscrew the cap.
It won't fly out, it'll vent before you can unscrew it far enough. As Pus mentioned, it's not that good for the seals so let out slowly. I had zero problems just venting but that was with an air rifle.