I checked and it's still leaking. I listened as best I could and the only thing I thought I could hear was a slight 'gas escaping' sound coming from the rear where the CO2 canister itself goes. To hear it I had to open the back up when the gas was installed and hold it up to my ear. The sound was there when the gas was fresh but it stopped after a few shots.

The gun was still empty after a few hours though.

Any ideas?