Thanks!

Some balanced valve development:



Balanced valve V1 and housing compared to the improved poppet and original housing.

Note the groove at the head of the valve to allow air to vent into the balanced portion.

The head diameter is also reduced to 6mm from 8mm for better flow.



Balanced valve V2 with a larger bore balanced portion to decrease the seating bias and allow operation at even higher pressure.

Diameter is increased from 7mm to 9mm and the housing is bored out accordingly.

Pumped it up to 1800 psi and shot it over the chrono.

The display showed 520 feet per second but I suspect this is erroneous as the lead ball went further into the wooden backstop than previous shots. The muzzle was probably too close to the first sensor on the chrono.

Loaded up a second shot and got an almighty whoosh, and this:



That works out at 84.2 ft lbs

The chamber was completely empty however, and subsequent evaluation revealed the reason:



It turns out that allowing the valve to bottom out and a relatively weak valve spring might not be the best ideas at this end of the performance spectrum...

I think a minor redesign will solve the issue, watch this space