No, I have all the upgraded parts.
I 'Think' I have sorted out the issue.
What I think happened was the CO2 plunger was just a tad too deep, which forced the 12g down onto the pierce pin just enough to break the seal, but not enough to properly open up the 12g. Thus the very slight leaking sound...
I just need to back out the plunger a tiny bit so that the 12g is only pierced on the first trigger pull...just like it is supposed to do!