Good post Matt,
Somewhat applicable as from what I can tell the Impact and Crown both use the same seat as the Boss. So far with my testing and reg pressure around 160 (I know a bit high) and with only 600mm barrels I've gotten;
62fpe in .22 with a 30gr
76fpe in .25 with a 43.2
The .22 is closer to your peak performance I wonder with the extra 4 inches of barrel how close it would be? I went from about 44fpe to 52 in the Royale by changing from the 500 to a 600mm. I think we are limited by the valve seat like you say and I agree, maybe the big upgrade would be to machine the blocks to accept a bigger valve seat other than that I'm not sure how much bigger the ID of the seat can go as Ernest seems to be at the limit.
I agree, the issue with larger valve seats is they are harder to open so that takes re-working of the hammer weight and or spring rating, but Ernest should have no issue down the road if that presents itself as the next obstacle.
FX sets up the valve currently to allow interchangeable calibers, which unfortunately throws a tiny wrench in the gears of peak performance. Its impossible to design 1 valve that works best in a .177 and a .30 cal without having a few other changes occur with the swap, such as valve seat/poppet geometry along with the other changes they currently implement.
Ideally you'd design the valve for your platforms largest caliber and have a design in place that restricts / limits wasted volume like a restriction plate / different sized transfer ports based on caliber. Barrel porting can achieve this but the volume from valve exit thru tp would be considered 'waste' so restricting air flow sooner is better for smaller calibers that don't need it. Not sure if the current FX valves have any restriction design in place, but with interchangeable calibers it should be. Even disregarding the wasted volume I believe its more critical to have adequate flow for a larger caliber than it is to lose a few fps and a shot or two on a small caliber. ie: build a valve for a .30 cal and work backwards or say eff it and let the barrel port restrict flow on smaller calibers, which simplifies hammer weight/spring ratios by not having 4 different valve seat / poppet geometries.
Glen...here are some numbers that may interest you. Top is current config of your .22 cal @ 160 bar 23.5 barrel with 30gr. Middle is 27.5" barrel with 30gr. Bottom is 27.5" barrel with 45 gr.