SpudFiles

Go to Fastenal. I have their HUGE catalog, I've ordered hundreds of dollars of pressure rated 3" fittings (on accident) and they don't cost more than they would if Home Depot sold them. Thing is, I now have a small inventory. An expensive one. And I felt bad about it, for a few minutes. But it wasn't MY money I was spending back then, so we all agreed it was a good thing.

Buy from Fastenal, their service is great (shit gets there when they say it will be there), their catalog is very large, and if you check there's probably one very close to you. Mines not outside three or four miles. =)

flexpvc had better prices for most of the fittings and some very unusual ones as well (like a 2in coupler with a strainer built into the middle). only thing is that on some computers it will randomly delete things from the cart.

Lentamentalisk wrote:Even if you were to find pressure rated fittings and pipe that size, you would be looking at hundreds of dollars. For example, a 3" PVC tee, rated at 150psi (McMaster part number 46885K158) costs $56

edit: and it comes with a warning:

WARNING
Never use plastic pipe fittings with compressed air or gas.

but still, we do that all the time, as you can see...

Thats because that is mcmaster...

...........

i agree with chressilvarmancs about the only needing one valve. i have one 4inch with 3inch porting on the cannon i am building and ggdt says that i should be able to shoot a soda can full of cement weighing 500 grams at 450fps i also have the male and female adaptors for interchangeable barrels on mine. also if you do make a 4inch piston a 3inch coupler shaved down a bit fits PERFECTLY!!! and i just use a neopreme seeling face