I've only had this .22 rifle for a short time, and it's proving to be a lot of fun.  First a quick rundown on my current setup.  No fancy accessories for me, just a Discovery optics 4-16 x 42 SFIR scope.
As for the tune, I have the hammer spring fully backed out, the regulator set at about 1700psi and this is getting me 70 full power shots.  I'm using JTS dead center 21.53 grain pellets, and they are being pushed at about 879 feet per second.  This creates almost 37 foot pounds of energy.
A brief list of pros and cons as I see them.
Cons:
Overall length makes it too long to be a convenient truck gun, which is a pity. Because I'm sure has a pest control tool it would be great.
The trigger on mine is certainly less than wonderful. The first stage is long and gritty, and the break is kind of uncertain.  In spite of that, i'm getting good results and I think I can improve over time as I get used to it.
You have to remove the buffer tube completely to get at the hammer adjustment screw.  It wasn't too much of an issue for me, as I didn't do an extensive tuning session with it.
Pros:  This rifle is capable of making a ton of power, and I realize I'm only using a fraction of it with my setup .  But I'm very pleased with the shot count vs. power so that's probably where I will leave the settings.
I think the accuracy is very good and in the hands of a better shooter, the results would be excellent. My groupings are 90% within 1/2 inch center to center at 40 yd, and for my needs, this is very good.
I like the texture of the stock. It has kind of a non slip a feel to it without being gritty, hard to explain just kind of silky.
Since there is no air tube or tank suspended below the barrel, it has a very interesting rifle-like look.
If you're considering this gun, I would encourage you to go ahead and get it.  I've attached several pictures.For your viewing pleasure. 😄


Barra 250Z current setup and tune