Quick question on these pistols please.

Has anyone had any issues with the CO2 cartridges they use. I've only just got my CP1 and at the moment I only have Crosman cartridges available and they don't seem to work in this pistol. I think the end cap is too hard so when it initially pierces I don't think it's tightening down on to the seal well enough and I'm just getting hissing from CO2 leaking into the action. It's either that or the valve itself is leaking...

Be interested to know people's thoughts.

Thanks in advance

Andy