New valve for regulated Hatsan in 22 cal

[taurusmk]

Hi all,
I'm new to this forum and relatively new in the PCP world, but I fall in love and now I'm reading for airguns whenever possible .

I have Hatsan bullboss in 22 cal for 6 months and I bought a regulator (from lane) to get more consistent shots.
Now I want to build completely new outlet valve that will be optimized for shooting JSB heavies 18.13 gr at 900fps but after hours and hours reading about outlet valves I have headache now.
Can't decide about keep the same valve pin diameter and valve throat or increase them (current are 3.5mm (0.138') pin at front(where the hammer hits), 2.5mm(0.1') pin steam and 4.4mm(0.173') valve throat diameter, transfer port 4mm (0.1575'))).

Any suggestions for port size, valve throat and valve pin diameter for best efficiency in 22 cal 33fpe?

[taurusmk]

Anybody? 
I searched for info in the forum, found a lot of guidelines but nothing specific in numbers.

Considering the pin steam is 2.5mm I think that 5.2mm overall diameter of the valve throat(seat) will be the best because it gives an area 16.3mm˛ which is 12% larger than transfer port area and
almost equal with the area between barrel and pellet probe.
Required force to open at 135bar (regulated) is less then required force to open at 200bar when fitted with the factory valve with 4.4mm valve throat(seat), so I don't expect big changes in behavior when  hammer hits the valve (closing force is same as factory valve when at 135bar).

If I made a mistake somewhere in my assumptions please let know.

Thanks in advance 

[taurusmk]

I decided to go with 4.2mm transfer port and 5mm valve throat.
This the design, it will be made from aluminium alloy 6082 T6 and today will be finished and tested in the next days
If anyone is interested in doing something similar feel free to contact me for sharing the experience.