I'd try and dial in a tune at 140 bar or so. You'll find good consistency here due to the factory hammer weight. Dial it in for 900 FPS if the rules will allow. This speed is going to see the least amount of wind drift for a projectile in the .03 BC range.
The hammer spring setting is the least important. You want the hammer weight (which is fixed) to be in balance with the valve pressure. (around 135-140bar bar on this gun.)
The wild card will always be harmonics. We can dial everything in where it should be ideally, and still find that the projectile is leaving the barrel on a harmonic node. More frequently disturbing the departure of the projectile. We can remedy this a bit by bonding the liner with a stiff material. To this end, Earnest Rowe sells some carbon fiber tubing that will fit FX liners, but I'm not sure he makes them for .177.... We can also adjust the tune a little bit to move the departure off of the harmonic node. This will be able to be observed in actual group tightness on target.
Now, the other thing... is that hammer cycle can be disruptive to the gun while it is firing. The nice thing about the Crown is that it has a semi-balanced valve that does not require a whole lot of force to open.... so the hammer is relatively light, as is the hammer stroke. I run my gun with very high hammer spring tension, and it is not disruptive to my shot cycle. I don't shoot competitively, I but I can definitively say that the gun shoots worlds better than any of my others, for the soft shot cycle alone. (not to count other advantages it has)
Now there should be a good efficiency zone around 120 bar as well (speaking of consistent velocity) tuning for 900 fps here may allow for softer hammer spring settings. That may or may not be a good thing.
