Can I make a cannon using an in-line valve? Im having lots and lots of trouble finding u shaped valves. I only found these, and they have low pressure ratings.
http://www.sprinkler.com/buy/item/irritrol_r_valves/2792
http://www.sprinklerwarehouse.com/RainBird-ASVF-Series-Valves-p/100-asvf.htm

I ...

I understand now :). I am a beginner so I couldn't really do much. I had no idea where to start. And I did read up on cannons, but I didn't know any helpfull websites or anything. I built combustion cannons before, but this is totally different.

Also Im wondering since I can't find 2.5'' pvc, what ...

Ok cool. So I can follow the directions to the firing mechanism on that link earlier. If the barrels is threaded and can be screwed in, then it can be breech loaded, right? What size chambers should I buy if I want to have interchangable barrels for soda cans, bottles, golf balls, and or tennis balls.

If I have dual chambers I just put the schrader in one of the valves? And the modded valve... where do I get that? Or can I mod it myself? HOw would I operate the un-modded valve?

What can I shoot soda cans with? Or Soda bottles? And where do i put the shcrader valve? Does the sprinkler valve have to be modded? Or can I buy one ready to use?

Under the barrel would be much better. Ok then, I understand. How do you connect two seperate chambers under the gun? And what dimentions would you recommend for the the chambers? And last, can you buy a one inch sprinkler valve at Home Depot?

Im going to Home Depot today to get parts for a smaller version of one of the cannons I posted earlier or a smaller version of the mega cannon you guys planned out for me. But after that Im gonna make the mega cannon. I have like 3 hours to come up with the list of parts and plans for the cannon ...

My friend said hes wants to make one or two smaller super cannons before making a huge mega cannon. He wants to find a cheaper valve less than the mauler, but still reliable. I also want to make those breech loaded. He is doing the funding for these cannons so he said keep the smaller ones pretty ...

Ill go with your idea, the compression union. So I will buy 3" parts. If I buy 3" parts then I have to use 3" parts throughout the entire cannon? And I can have an interchangable barrels, right?

What do I do with that? How could I build one myself? And what do I connect to what with the valves?

For the breech loading PVC Arsenal 17 showed earlier, what do I need? That type of loading seems easier.

Ok, once I find out what I need for the breech loader I will call my friend and we will go to the hardware store and buy what you said to. If we can't find the mauler valve we will order it online.

Ok, Thanks for the advice. I don't really understand what it means to pilot the mauler valve with? What is a modded sprinkler valve or QEV? And what do I do with them once I get them? How can I set up that breech loader on the cannon? Well, actually i should probably get the parts I need for it ...

There are two types of mauler valves, 3 way button or 3 way ball thingy. Both with schrader valves. Which do you recommend?

We are conquering the seas. No, my friend bought a small yacht and he wants to do something with it. So he decided to make a pirate ship. He is adding on wood and a sail and everything. He has a little beach on he property also so we are gonna sail to his house. We are going to do target practice ...