So from the bottom of the Reg Valve ( what the bevillelle washer's sit on) to the top of the stack 15.75mm.
This measurement is Crucial as a fraction to much will lock the valve, less and you won't get the pressure needed. You have experiment a little to get the best set up.
Firing valve ⬅)(())()()()(➡Air Cylinder.
Steyr Hunter HFT/ HW 100 barrel + s111 & SS buttplate. HW100Kt+ SWFA ss 10x42......Shooting HFT for MVAC.