[MrForbes]

well....not quite! imagine that you have the cylinder in a mechanism in a way that it is not fully extended or contracted when it is at the end of it's travel (it's travel is limited by the mechanism). The pressurized side can hold quite a bit of energy. Enough to launch the ball, if you have a pair of 2" bore cylinders with at least 8" total stroke, and starting out extended about 1/3 of the way.

at least that's what our calculations show.

But we're going to start with the shooting side of the cylinders unpressurized.