Fun! However I'm doubtful it is an antique. There are mini cannons with no functional purpose other than to make a bang and shoot a golf ball (or whatever will fit down the bore) and I think that is what you have there. We have a little one in our pirate reenactment group that measures about 4" and has been nicknamed "Pee-Wee". It is a lot of fun to put Pee-Wee in a line-up of cannons and make a big fuss like we're scared to touch it off then it gives this heroic "POP!" as if it is trying sooo hard to compete with the big cannons and everyone gets a really good laugh out of it. They make these for reenactment groups/cannon enthusiasts. Generally they are sold without the touch hole having been drilled through and the purchaser has to take care of that themselves. The hardware looks modern, and the carriage looks to have been cut with moder power tools. The wood looks like it was scorched to appear older. and if I'm not mistaken, it is mounted on plywood rather than solid wood (can't say for sure looking at the photo).
That said, you can have a whole lot of fun with this one, whereas if it were antique it would probably not be safe to fire. So mount it on the rail of your apartment balcony, dress up like a pirate and shout out "FIRE IN THE HOLE!" when you touch the little guy off!
