Located in the eastern US

Where do you guys find 3 and 4" pressure rated PVC? The only 4" PVC that Lowes had was the cell core stuff that isn't built to take pressure.

Actually, I'd rather have a set up like this:

http://supersoda.com/content/images/000 ... 001423.JPG

Does anyone know what fittings those are? Some kind of 1/4" to 1/2" threaded adapter? And then a 1" x 1/2" tee?

I guess semi-auto isn't as important to me as the ability to get off multiple shots relatively quickly. If it takes a few seconds to refill the chamber, that's fine.

I want to do something like this:

http://supersoda.com/content/images/00000000094/000000000943.JPG

How hard is it to install a ...

Is it really necessary to modify the sprinkler valve? How well would it work with just the solenoid trigger? I'm on a limited budget and don't have access to things like taps.

I want to build a simple air cannon that can fire multiple shots (5 ish) off a single air fill. I was thinking some sort of 2 chamber design where 1 chamber can be used to re-fill the other one after each shot.

What is the simplest and cheapest way to achieve this?

Just buy a small air compressor from Lowe's/Home Depot for around $60. Don't get any of those 12v mini compressors that will eventually break. They will not fill to 200psi like they say.

So basically you are just making 5 different guns. That's not really semi automatic.

I like to plumb my fittings into my cannon to reduce the leaking and or flying fittings problem. Here is how I mounted my pressure gauge. I did the same with my Schrader (tire) valve.

<a href="http://www.flickr.com/photos/carlbelcher/167592506/" title="Photo Sharing"><img src="http://static.flickr ...

I believe 3/4" PVC is slightly larger than 3/4" CPVC, so paintballs will fit in both, but it is a better fit in CPVC.

First of all, I'm not trying to act like I know more than you, but I wouldn't be surprised. I am stating that I find it funny that you are bragging about your ion, how it's a "high end gun" and it has the "1st or 2nd most expensive tank".

Co2's max pressure (which is over 1500psi)

The pressure ...

Lol, it's an Ion. It may seem pretty awesome, but most speedballers would strongly disagree. Mainly because the body is made of plastic and they retail for $200 so all the noobs bought them.

Thanks for the tip. I've noticed that most people use sprinkler valves for their pnuematic guns. Could you explain to me how that valve works and how people modify it to make it work better. Does it really work that much better than a ball valve?

Thanks for the tips. I actually built a simple pnuematic cannon today. For the tire valve, I just drilled a hole in the cap and pulled it through. I used a rubber/plastic glue to seal it to the cap. The gun itself works very well, it will launch a "AA" battery a good distance.

http://img ...

A small hand pump could probably get up to 40-50 psi if you were really pumping hard. Once you get more involved in building cannons, it is probably worth it to invest in an air compressor.

The other thing is that if you want an easy to make gun that you can use inside, you should look into the ...