The cannons I have seen throughout my travels I have often wondered what size the actual shot was. I have also wondered how much it literally would ruin your day getting hit by one. I took this pic while I was in Panama specifically to remember to gauge the actual size of the bore on a large cannon. Using a ruler next to my hand I guestimated the bore to be about 6-7."
I had recently been forced kicking and screaming to accompany some of my co-workers to see the Yorktown Victory Center. While there we actually went outside where they had a living museum type of setup. There were several people dressed in traditional clothing of the time. While this literally means nothing about your subject they did have someone who was playing with muskets and they said the general rule of thumb for effective range on a smooth bore musket was about 100' or less.