Thanks for the detailed explanation jimmy!
I was really only thinking of using the ball valve because I couldn't find an alternative with a 2" diameter. I suppose that's why piston valves are popular. I watched a video where a guy made his piston out of bondo. I will go with another sprinkler valve ...

Thanks for the suggestions fellas!
The piston valve is something I may have to work up to. It seems a bit complicated to me, with my current level of experience!
The valve on my launcher is indeed 1". Would the ideal valve diameter be the same as the barrel's?
My laptop crapped out on me so I've ...

Hello good people!
My job requires running fiber optic lines over great distances in rough terrain. A device that could launch a string 500-600 ft would be a great help to me.
I built my first pneumatic cannon last week and although it wasn't as powerful as I had hoped, the results were encouraging ...