Hammer spring preload makes a HUGE difference in a regulated gun, not to power, but to shot count.... If you leave the preload adjusted for 200 bar and then run the gun at 100-120 bar, you will be wasting nearly half the air.... You have to drastically back off the hammer strike when you drop the pressure, otherwise you will not reach your expected shot count.... You may have to fit a weaker hammer spring, or shorten the one you have to accomplish this....Bob
Hey BD,My guess (with help from the airgun calculator), is that you should be able to get 50 regulated shots with 15.99 JSB's at 870 fps using the 230cc aircylinder. Definitely, 50+ shots at 850 fps. This assumes you lose 50cc's to the regulator and plenum. To achieve this you will need to complete the valve work outlined and tune the gun on the "knee" of the velocity curve using the preload adjustment as Bob/Baxter have suggested.Good Luck