Hi Zippo
Leaving a cylinder in the gun is asking for the seals to fail. They will EVENTUALLY fail but the pressure needed to hold the cylinder against the seal will compress a groove into the seal and you then start to lose pressure as soon as the new cylinder is put in.
If you take the gun out of the house then having a cylinder in it whilst you are transporting it is illegal and constitutes a firearms offence. The magazine, or spare ones must not be loaded whether they are in the gun or not.
Ignorant? No. We all started this way, some of us long before others and with a totally different set of rules.
You, at least, have had the sense to ask for information.
Enjoy you guns and "waste" any remaining CO2 by shooting more pellets.
Target Bunny