Try a mid cap. Also, shoot the gun without a mag and watch how the nozzle cycles inside the mag well. I had a simmilar issue with my G36 till I modded the tappet plate, but thats a different beast. I'm planning to take it down monday/tuesday and do the same mod to my SL9 if you want to see what I'm talking about. Basically you just cut the bottom off so that there is no '2-stage' action when the nozzle moves forward.