paintball cannon rounds

I have a question on the paintball cannon. How do you get a (nearly)
airtight seal on the rounds so the co2 won't escape? I have tried multiple
kinds of wadding, but can't get a good seal. what ya'll think?

don't use wadding.

Use a foam rubber football as a projectile.

Styrofoam cups don't work?  How big is your bore?

Two styrofoam cups have always worked for me.  Place the sealing cup upside-down in the barrel so that the open end goes in first and put the second cup with the paintball shot on top of it.  When you shoot, the bottom cup will expand slightly and help seal the bore.  If this still doesnt work, swab the barrel with vegtable oil.

i got this from: http://www.corin.com/bill/paintball/aircannon/

dunn onot my idea. my launcher is gona launch squadbusters

 

I messed around a bit with my spudgun and paintball-launching (much too hot for field use). With a 1.5" bore, 3L soda bottle caps seemed to fit perfectly. I then made a bunch of sabots from cardboard and cardboard rings to hold them together until loading, topped them with paper towels. It could fit about 20 ball, or a balloon filled with crayola washable paint and some corn starch if you twisted it into sections. Also tried to not tie off the balloon and instead twisted it and stuck a small rectangle of cardboard onto the back so it would untwist in flight and air-burst, but it wasn't too reliable.