My Homemade Air Cannon.

This is a very simple and cheap air cannon that I built. If you have an idea to fix the leaking problem or suggestions for ammo please tell me! : )
This is the list of materials I used.
1: 1/4threaded compressor barb(came in an accesory pack)
2: 4ft long 1in in diameter pvc (cut in 2ft pieces)
3: 1in ball valve
4: pvc cement and primer
5: 1in end cap
6: drill and 1/4in drill bit
7: tire pump
8: hot glue gun and hot glue sticks
9: duct tape (one of mans greatest accomplishments)
If you can't follow the picture, I have a video on youtube (I had problems putting it on instructables)

1: Drill the end cap, then screw in the compressor barb in ( be carefull because the end cap can crack)
2: Cut the 4ft pvc in 2ft sections
3: Cement the two pieces of pvc the the ball valve, then cement the end cap
4: Cut the tip of the tire pump tube. The tip is right under the small device that connects the tube to the tire
5: Connect the tube to the barb then hot glue it and duct tape it
6: Let it all dry
7: Test it out!
For ammo I use rolled up paper tubes that are twisted on one side and stuffed with a napkin or a paper towel