Shannon
Haha, I bought my ex one. We just shot it till the gas was completely gone.

Helix
Gas should always be emptied after a skirmish, primarily for safety reasons. Most magazines have a gas release mechanism for this purpose. It can vary from gun to gun, but try looking near the bottom of the magazine. Once the gas has been discharged, the magazine should still be stored outside the mag well. That is, don't place the mag back in the gun as this indicates that it is loaded.

Buster
It is a common misconception to fully empty the gas out of your magazines. You should leave a little gas in your magazine when it's not in use. This better preserves your tank as well as keeps a proper seal. I often put a quick spray of gas into my magazines and fire off about 3 shots then release the hammer on the pistol before putting it away until the next weekend. The internal tank inside your magazine is made to regulate pressure so it doesn't break seals, but that's not to say leave it fully gassed for days or weeks on end. If/When your O-rings break, just go to Home Depot or other store and get some cheap O-rings and replace them to fix any leaks. There are tutorials of this on youtube.

Joe Jeronimo
Check this out . It has great info that helps me with all my gas guns. I hope this helps you too.

Juice Ortiz
In that situation you will want to release the gas from the mag using the release valve on the back of the mag at the top side. You will need to release almost all of the gas and leave a little bit in it so it can keep all the seals in place, Here take a look at this link has tons of info