As I mentioned in my OP, the valve was initially used on a gun that used a 4" chamber and the same type of valve and that worked so it should be more than adequate for the 2" chamber. I'll pick up some epoxy and see what I can do with my backup valve. Hopefully that will do it.

Hello all.. I don't know if anyone remembers me but I've been spudgunning since the old old spudtech forums were up.. got a problem with a new gun I built. Its got a 7' 1" SCH80 barrel and a 5' 2" SCH40 chamber, coaxial. The 2" has a male adaptor hooked up to it and the barrel extends just beyond ...

You guys are getting way too technical now, it doesn't make a damn bit of difference whether the air goes through the stock or not performance wise. Check it on a chrony...

Wow! Hard to believe there's still interest in this.

If you end up doing this, be forewarned-the discs leak since the unions are only designed to seal one way. I ended up having the unions milled so I could use another(thinner) o-ring on the other side and it worked fine.

To answer the volume ...