Just to be sure, you're filling through the ball valve side of the piston correct?
Also, your piston may not be the correct diameter for your tee; or if you have an equalization hole in your piston it may be to large.

Freezing paintballs is a pointless endeavor, they don't get harder they get brittle. http://www.youtube.com/watch?v=yyXXXCC3B0E

I would try some dowel slugs.

Mobile, this is quite a beautiful cannon. I was actually planning a cannon using a cross as the valve before I saw your threads, quick question for you; is that your final piston? or does it have o-rings?

Calvin

Here is a good example of a quick connect: http://www.homedepot.com/webapp/wcs/sto ... 401+527603

Alternatively you can pour some some pvc cement into the solenoids hole let it dry for an hour then top it off and let it dry over night. It's not as permanent as epoxy but it seals it off pretty well.

Awesome, you'll be getting an order from me soon. Great website too by the way.

Hey gort, do you think you could come up with a 3" or 2.5" port porting valve?

Great first cannon dude, and an advanced combustion as well.