Well I made a smart decision today about my mini Asian cannon. Someone said that the bore was 4mm. Well, sort of? The firing of the actual cannon was a pipe bomb in the waiting. It may of had a 4mm hole at the muzzle, but the bore was more like 16mm. Now not being familiar with them, but wondering that this piece just may be a fire cracker cannon? Plenty of room inside the bore for one and just leave the fuse passing through the trough to be lit. Fire cracker goes bang, smoke comes out the small muzzle and you load it up again and light another one. I use to drop lit firecrackers into two liter soda bottles and it would have a muffled bang with smoke coming out the top and so on. But this certainly was NOT made to shoot anything at all. Smithy.