James A Michener actually writes about these guns in his book Chesapeake.
He describes how they hunted the ducks and geese - but mostly in winter - because during summer the geese would migrate. So they dragged their skiffs across the ice and they would find rafts of birds in the holes in the ice sleeping. Then they would get the skiff in the water, approach them and fire. He also describes how the Chesapeake retriever and a black Labrador would compete to try and get the most ducks.
It is actually a very good book for outdoors people like I'm sure most of us are. Here is a link. Use it or don't use it.
He has quite a few other books that are great as well. Just a hefty read of around 1000 pages ;) But really worth it.
https://oceanofpdf.com/authors/james-a-michener/pdf-epub-chesapeake-download-69751042164/
Cheers