Thanks for the input so far. I kind of knew the answer already before I posted my question, but I still wanted to get some input. I would prefer to use a barrel- or chamber-sealing design, rather than a ball valve. I was planning to slow down the shot by reducing the pressure, although I could also ...

I am looking to make a snowball cannon (just got 15-18" over the weekend). I would prefer to work in PVC, but that would be kind of dangerous in the cold weather. It would have to withstand up to 100psi at about 30 degrees F., and I would like the barrel to be on the order of 1.5" to 2" in diameter....

Any pictures/specifics on the joint in question? Some fittings may have enough room that you could drop in an o-ring.

Maverik94 - You must live in or near Michigan. I haven't had Vernor's in years! you can also go to a store that sells hunting supplies and buy lead balls in many calibers (.50, .45, .44, etc.). This will prevent that annoying habit of steel shot that will cause it to ricochet a hard surface and pop ...

I picked up a couple for $4 each on the clearance shelf at Lowes. Still working on what exactly to make them into...

For alternate ammo, you can find practice golfballs. They are made of foam, but often have a slightly denser core. Foam practice golf balls don't go very far. I used my big cannon with the 2 inch barrel with a 1.5 SDR21 sleeve (golf ball sleeve) and gave one a high power shot. It barely made the ou...

For alternate ammo, you can find practice golfballs. They are made of foam, but often have a slightly denser core.

A lot of the larger PVC sold at home centers is for drain use, so they sell "foam core" PVC. This is made lighter weight essentially by "whipping" the PVC during the moulding process to make it airy like foam (hence the name). As it is not solid material, it is not as strong. I know Lowes sells both...

Ifyou make the barrel tight fitting, you could probably hook up a vacuum chamber to the back to use to "suck" the cartridge down the barrel to the nail. It would be like a pneumatic cannon, just with the QEV backwards (QIV?). Although, if you're going to that much trouble, you might as well just mak...

Instead of an o-ring, see if you could find a v- or w-ring. That way, the pressure would help push the seal against the ball (sorry, I'm at work and can't draw a picture right now).