Are you shooting warm propane? It sounds like a light strike issue that you're having. Try chilling your mag in the fridge for 5-10min before shooting again. If that fixes the problem, then I'm guessing that your hammer spring isn't stiff enough to bash the firing pin far enough for your mag valve to acheive lockup. WA mags have a lock which holds the valve open until the slide recoils significantly.
If this is the problem, then try dropping a bb into your hammer spring well to increase the hammer spring preload. This hits my Guarder hammer spring sales, but it's a quick easy fix that works until really hot summer days.
Also check if your nozzle valve reed is moving freely. The bb pushes it rearwards. It's supposed to spring forwards when breech pressure drops sharply (no bb in barrel) and force the cycling of the slide.
__________________
Want nearly free GBB gas?
|