Best type of QEV? (and pilot/fill valve)

[al-xg]

The O-ring ( blue dots on my drawing ) is making an airtight seal with the inner tube whilst in initial position.
When the trigger is pulled, it moves back into the larger diameter pipe and looses its seal.

The middle O-ring does the same thing but the other way around.

The third O-ring is only there to equalise forces at high pressures.

[Hailfire753]

Doh. For some reason I was thinking "C" was the hole at the bottom, below "B". Whoops.

EDIT: Also, looking at the sleeve valve more, I don't think it is really plausible. I would use 1" sch40 pvc with 2 3/4" tees, plus 1 drilled hole for pilot exhaust. Not very compact, and inconvenient port placement. The blowgun-QEV setup seems much more convenient, but I have not thought of a way to use the pilot air for a response trigger.

Would the airloss in this setup occur through the barrel or through the pilot?