Tuning a 5.5mm/.22 Diana Stormrider for maximum power

[PCPdude]

Hey guys,

I recently purchased a Gen 2 Diana Stormrider because it is an air gun with a very simple design which should make it easier to learn how it works and tune it to my needs.
Currently, I am trying to find the maximum power it can produce without paying any attention to accuracy. I want to find the maximum power it can produce, then back off on power to merge power and accuracy.

So far I have ensured that valve, transfer port and the barrel opening are the same diameter and I have removed any sharp edges with wet sand paper. I also installed a Lance regulator and can produce around 30J / 22ftlbs using JSB KnockOut slugs in .216
I have tried a stronger and weaker hammer spring compared to the stock spring but the power is reduced with either one. So is 30J/22flbs the maximum this air gun can produce?

As far as I can tell the transfer hole in the barrel is the limiting factor as there is no more room between the hole and the orings.
What is you experience with it? What is the maximum power you got out of this PCP?

Shooting a slug into a barrel of water produced this .... ouch

 

[Guest]

You will find quite a bit on them if you start looking around the forum.

https://www.airgunnation.com/topic/stormrider-experiences/

Here is a place you can start. It's a .177 but I got 26 FPE out of mine with no tuning.

 

[cklein]

I get 831 FPS with no tuning and great shot count of 51 shots in a ,22 JSB Exact 14.4 gr pellet and very accurate! No regulator! No second barrel band! I have not modified it at all! 

 

[Jesfranco]

I am getting 825 with JSB 18.13 . The only thing I did was open the transport port a little . Less shots count but is ok !