spudnutbutthut wrote:BTW how much PSI do you need to run a cloud shooting .2s at like 350 fps?
You might as well ask me "How many horsepower do you need to get from 0-60 mph in under 5 seconds?"*
There's missing information in the question. In your case, barrel length, barrel tightness, cloud chamber volume, actual regulator flow... all of these things change muzzle velocity in a cloud.
It's not impossible to get these things to work with propane, but it is trouble, because it draws off pressure very fast, thus causing tank temperature to drop dramatically - thus losing pressure.
I recall seeing one that did work (although I think it was a vortex, the basics of the gas system are identical) in the old archives of either here or Spudtech, but I can't immediately find it. There are however still all of those references to problems which I can find.
*The answer by the way, is none.** I just lob you off a tall building, and you'd be doing 60 mph in under 3 seconds.
** To the pedantic - shut up.