This is just a short post about how hammer strike affects a regulated HPA gun.... There is an optimum balance between regulator setpoint and the hammer strike, just as in a non-regulated PCP.... Adding spring preload (or hammer travel or weight) past a certain point will result in the gun using more air, but no increase in velocity.... Here is an example....
You will note that there is no change in velocity past a certain point as you increase hammer spring preload.... but the efficiency goes down (number of shots per fill goes down) because you are just wasting air.... However, if you go too light on the preload for a given regulator pressure, once the pressure drops below the setpoint, the velocity will actually increase instead of falling off like it normally does.... Here is an example....
You will notice that when the tank pressure is above the regulator setpoint (in this case 1500 psi) the velocity slowly creeps upwards.... and then once the pressure drops below 1500 psi it climbs quickly before falling off again.... Most regulators have a small amount of "creep", which means that the output pressure is very slightly higher when there is 3000 psi in the tank than when there is less.... Since the hammer strike is very light, that slightly higher pressure keeps the valve from opening quite as far, resulting in a slightly lower velocity.... Once the pressure drops below the setpoint, the valve opens more and more, and the velocity increases, just as in a non-regulated PCP.... Once the velocity peaks, then the velocity drops as the pressure once again falls.... If you are in this situation, the ideal solution is to lower the regulator pressure to where the peak of the velocity occurs, or even less if that is still more velocity than you want/need.... In the above example, the velocity peaks at 840 fps at 1200 psi, so if you want velocities in the 800-820 fps range that would be a good choice for the setpoint....
I hope that understanding this relationship will enable you to get the most out of your regulated HPA gun....
Bob