Oftentimes those guns would be mounted on walls of forts and used to "snipe" at artillery crews. Most were around a 1 inch bore. They have several of those on display at Williamsburg. Pretty impressive.

I wonder what charge and what weight projectile they were using?

Here is a little more history and story about guns and hunting on Lake Erie I mentioned in the above post. Winous Point Hunting Club. There was also a small wildlife migratory bird museum a Crane Creek Marsh west of Port Clinton, which was (is ???) a state marsh. It has a lot of history there.

https://www.cleveland.com/outdoors/2016/08/rare_decoys_local_waterfowl_hu.html

Garry-

If the single ball weighed a quarter-pound, then it would be a "4 gauge". The gauge part, now almost just restricted to a shotgun label ammo, comes from "how much shot did it take to make a pound?' You can see how this works in an 12 gauge shell if the shot load was 1.33 ounces. Similar in a 20 gauge with 8/10ths of an ounce per round, pretty close to the 7/8 oz in a lot of old standard lead loads.

If you've ever read James Mitchner's book "Chesapeake, the use of a boat mounted "punt gun" shotgun reoccurs in the story. Sometimes when the Baltimore market was "hot" for waterfowl, the gun's multi-generational owners would "double charge" it with both powder and shot. They used burlap sacks filled with fresh pine bows to reduce the recoil to the back of the lay-out boat.

Thank you for that information... I am not much into the statistics or ballistics. I just tell the stories as I have heard or seen. The old man that demonstrated the gun his father and grandfather had shot... was asked about the shot, and told that they shot any metal pieces they could get stuffed down the barrel... that sometimes they could get enough lead shot... so they just used whatever they had. The gun he shot for us I don't believe a flint lock, but a percussion cap, but it roared like the flint lock in video, and laid down a pattern that looked like a tornado touching down. He of course wasn't shooting at anything in his demonstration, just showing a pattern.

Garry-