Air pulse duration, does it matter?

[tor47]

Great information. I think what I really want to find out, is:

1. low pressure long duration (say until the pellet has travelled 90% of the barrel before the valve shuts) or,

2. high pressure short duration (say the pellet has travelled only 30 or 40% of the barrel before the valve shuts). Or, even:

3. compare a third case where the valve doesn’t shut until after the pellet leaves the barrel.

In the first case the pressure only decreases slightly before exit. In the second case the pressure will have decreased significantly before exit. And in the third case the pressure will not have decreased at all prior to exit.

Which is best for accuracy? Does it even matter? Which is best for efficiency?

I am not an expert, but from a logical standpoint, regarding harmonics and accuracy: If you predetermine the speed (900fps?), and how far the pellet shall travel (90%), and at the same time expecting to hit a harmonic node (or whatever it is called) for best accuracy, is like wining the lottery. To find the harmonic node for best accuracy, there is basically two options: Either lower the speed of the pellet less than 900fps in this case, with less hammer force, until you find it. Or increase regpressure, and hammer strike until you hit the node close to 900fps. Going back to the lottery scenario, it is probably more likely you will be under the 90% travel for that to happen.

If we for instance wanted to lock ourself close to the 90% travel, I believe we probably had to start at much lower velocity, and tune for 90% travel with both regpressure and hammer, over and over again, until we found that node. Maybe do it with 5 bar repressure increase every time, and slowly increase speed with more hammer force? But in this scenario we probably had to live with whatever speed that might turned out to be. So if we "hoped" for 900fps, we might had to use 750, or 820?