Hmm. At 60 psi, GGDT is telling me that using a 3/4" QEV (The biggest I see on McMaster) would basically cut the power in half. Whereas a 2" barrel-seal piston valve with "default" params should get 306 ft/s, a .75" QEV with 7.84 Cv and .1g piston mass maxes out at about 180. I don't really need the ...

Thank you, socoj2!

By "really light", I assume you mean the weight of the poppet? I guess I'll fiddle around with it.

After yet more searching, I still can't figure out how to tell GGDT that I'm using a QEV. I'm sure I'm not the first person to ever try this. Would someone throw me a bone here?

In light of socoj's recommendation, I'll definitely scale this thing down. Before I figure the final numbers, though, I have two more questions. First, would a change of form factor be advisable to avoid bending the airflow? Second, how does one input "QEV" into GGDT? Is it "Generic"? What are ...

I searched again, and I found the ones you're talking about; thanks.

I'll be firing from anywhere from 30 to 200 feet; below 50 I would just as soon pull out a Nerf sidearm.

Imagine a 30gram paintball hitting you at 330fps.
In all fairness, a soft foam rocket would probably sting less, but I see your point. :)

Is a 3/4" or 1/2" QEV the size used to upgrade ...

I'm looking to build a cannon to fire Nerf Pocket Vortex footballs. The targets will be people, so obviously it has to be reasonably weak. Furthermore, I will pump it by hand, so the pressure has to be within the range of a floor pump.

From this, I need a 2" Sch. 40 PVC barrel. (All subsequent ...