The way the valves are factory (from Dukie, anyway), they were cupped at a very low angle, which leaves a lot of surface area to seal against the face. This prevents the guns from sealing at all below 500psi.
I back cut the valve face, and leave only a small, deliberate bit of material around the edges for it to seal against. Which gets the sealing pressure down. Which can let you shoot a bit deeper into each 12 gram.
Hooligan just had me do two of his, and one of them he took to D-day this week. We'll see how he feels about it when he gets back.