Originally Posted by Eli
Or run a regulator....
Werd. Newer WGP guns are not designed to handle unregulated CO2. What's happening is that with the IVG at it's "lowest" (furthest out) setting, the pressure in the valve chamber is preventing the valve from opening enough. There's sort of a "breaking point" at which the weight of the mainspring will overcome the pressure in the chamber, but then it's also overcoming the valvespring, so you've got too much gas flowing through the valve. You can try swapping around springs to find the right combination or use a regulator to bring the input down to around 400 PSI, which is what stock WGP valves & springs are really designed to work with.