Thought I'd share this for anyone who might be interested................
Here's a couple of videos from late this evening when we tested my younger son's mini cannon he made in shop class back in 2010. In class, he could do everything at school but drill the barrel out. He had a friend with a lathe drill it out last week to around .68 caliber. Barrel is about 8" long.
We loaded it with small loads and worked up to what is in the video, 200 grains of Pyrodex behind packed paper towels. We did not use a projectile of any type.
I wish my camera had better sound recording because the video does not do the little guy justice.......it gave off quite a boom and concussion for such a small cannon.
**Our neighbor from down the road has a 2" bore cannon we are supposed to fire soon, so I'll be sure to post video for those interested.