Well, you're using 134A green gas I assume. Try using a propane or something with not as much lubricant already inside the bottle.
What's probably happenening is as that power shot is being released, the little amounts of silicon that they put in each bottle is getting misted on that hop up, and making it slippery to the point of ineffectiveness.
I'd suggest running a swab or paper towel or what-have-you in the barrel and seeing if you have a lot of lubricant inside there. That's the only real problem I can see with the accuracy, having something in the barrel such as a semi-cracked bb fragment or even too much silicon will greatly effect accuracy.
If that is the problem, I'd suggest switching over to propane, while only putting a set amount of lubricant before every game, as well as a little bit onto the tip of the can, so that it helps keep the seal good inside the mag.
If that helped, feel free to Exault me
-Mosin