SpudFiles

From those pictures, it looks like the barrel is way too small (diameter wise) for the chamber. Of course, I may be seeing things.

From the design of the gun and with no support (I usually use a bit of 1" PVC as a support between the chamber and the barrel with a cable tie around it to keep everything from moving) it was definitely stress. Although the brand is also cheap from what I have heard.

I found out what happened. i didn't put any wadding behind the marble and it fell back past the elbow. when i shot it the marble came straight up and hit the elbow.

That might explain it. Put a small screw in the top of the elbow sometime, to make sure ammo doesn't fall down again.

pat123 wrote:I found out what happened. i didn't put any wadding behind the marble and it fell back past the elbow. when i shot it the marble came straight up and hit the elbow.

That'll do it. You might try a ball detent with your next cannon. You can do that by glueing a small piece of felt on the inside of the barrel where you want the ball to stop, or it can be done with a bead of hot glue. Just make sure that whatever you put in there isnt too large or it will restrict the airflow.

Edit, one thing that would work very well is if you took a small, think nail an dcut it to just a hair longer than the ID of the barrel, then jam it in there good at the back. As long as you can't move it easily with your fingers, it'll work great.