OK, you QB Gurus.... the standard setup is for the Valve O-ring to be tightened into the tube by snugging the two halves of the valve up once installed.... Any reason you couldn't use a standard 70D O-ring in the groove made between the two valve halves, adjusted for a bit of "squish", and then slid into place like the valve in a Disco?.... I'm talking HPA here, not CO2....

Bob