Wow, those were some quick replies!!

rmich732:
I was thinking of using a 4" tee but is there any reason I shouldn't? It's bigger so it should be less of a bottle neck (I would think) and it should require less fittings/adapters than a 3" tee.

Pete Zaria:
I have a 10ft x 4" inch piece of pipe I'm ...

I'm building my first pneumatic launcher after several combustion launchers. I have two questions:
What is the recommended chamber to barrel ratio for a pneumatic launcher? I have a 10ft x 3" barrel what should the length of the chamber be if it is 4" PVC?

Second, I'm going to be making a "Barrel ...