Alright, thanks for the tip I was going to make the same weight Ernest Rowe did, 8.25gr And likely still will. I might make it a bit shorter, though, and see how it does with 5 gr.
Welp, I took the gun out of the safe last night to show it to someone and it's down 50bar. Looks like the 'fix' and 'upgrade to mkii' didn't go as planned.
Taking it back apart and shipping it off to FX again