CO2 Related Problems:
Not all CO2 cartridges are created equal, they often have slightly different shaped nubs on them and some brands will work better than others in different Airguns. If the shape of the CO2 nub does not fit properly into the valve area then it may not pierce or it could pierce but then not allow you to tighten it all the way losing all the CO2 in the process. If the CO2 is coming form the airguns handle to CO2 Valve area then this is an indication that your problem is related to the area where the CO2 enters the airgun.
There is a seal where the CO2 cartridge buts up to the valve, this seal can be damaged or even deformed from usage or even leaving your CO2 in the gun for too long. The outside CO2 Valve seal can also take the shape of a specific CO2 nub so when you use a different brand CO2 the seal may not properly make concat with the new CO2 type you are using, again causing leaking or even the total loss of all your CO2. Watch my YouTube video on “How to Fix Leaking CO2 in an Airgun”.
CO2 Valve Related Problems:
Again, make sure that Outside CO2 Valve Seal is in good condition and any leaking is not being caused by this problem, if you have checked the Out Side Seal and everything is OK with it then perhaps there is a problem with the CO2 valve?
One indication that your CO2 Valve might be the culprit is the total loss of all your CO2 when you try to insert and tighten a new CO2 Cartridge. Usually all the CO2 will exit the barrel, not the handle or valve area. What may be happening is the valve is stuck open or the internal seal is broken or deformed. If this is the case you will have to remove the valve and have a look inside, this is a lot easier on CO2 airguns that have the CO2 valve in the magazine, if the CO2 valve is in the actual Airguns then a lot more disassembly may be required and I would recommend an Airgun technician take care of this for you.
If the gavel is in the magazine then you will have to unscrew it, you may require a special tool for this? Once the valve is out of the magazine take a look inside and examine the internal seal, also look for any bits of metal shavings as they can disrupt the action of the valve causing leaking. Give the inside of the valve a good clean and then lubricate it with some silence spray. hopefully that fixes your problem!