I have used ping pong balls as ammo with sch40 1.5 in., so that will work. I have a question though, do you want this to work like a shotgun? I mean do you want the bb's to scatter as they leave the barrel? If you do, then you would need to split the ping pong ball so it will come apart outside of t...

Thanks John, I 'll do some searching to see if I can build or find something like that. It's very simlar to the way tape measure is pulled back into the casing. Thanks.

You could also have a sharpened barrel which was fixed. Then you could use something to push the cartridge's burst disk against the back part of the barrel making it rupture. How about having the barrel push back? Both idea's are good, but I want the barrel to be larger than the burst disk cartridg...

The projectile won't be loaded into the burst disc shell, I will either muzzle load or breech load. Sorry for not specifying. Also, the shells will be rotated manually unless I can make something to do it automatically. If anybody has idea's for that, I'd like to her them.

I've decided to go with a lever system. Although I might go with a solenoid trigger since it's much less complicated. Where can you buy a solenoid? Here's a diagram of the trigger system. The individual parts have unique colors so it's easier to understand, although it's very simple.

I'm building my second cannon (first used ball valve). I have a rotating shell design similar to Solar's Eclipse. It will be using Davidvaini's burst disk cartridge design. Unlike David's design, i want to trigger by puncturing the disc rather than pressurizing until burst. My problem is I can't thi...