So I finally gassed up the Cp3 cylinder (Special trip to fire extinguisher place) and literally 2 minutes before I could get it attatched to the gun the internal cylinder seal in the valve appears to have gone. So an intertaining few seconds as the cylinder tried to escape my grip then freeze itself to it.
I am so gutted. I may as well start working on the 12-gram converter if I am ever going to fire this pistol at a target.