Miller,
True that. While researching a 20 gauge Prandelli & Gasperini (Richland Arms) double I came into a while back, I found an article by Francis E. Sell in the 1977 Gun Digest, titled "The Twenty Comes of Age" detailing his notion of using the 20 with big lead loads for geese and ducks. Within three hunting seasons, most of what he wrote was obsolete with regards to waterfowling and heavy loads of lead shot.
The same issue had an article on the then new Ithaca 3 1/2" Mag 10, an ominus bellwether of things to come.
About 1978, or so, I used a Remington model 17, with 2 3/4" high brass loads of lead 6s, to hunt ducks near Cold Spring, MN., on a small private lake with a maximum depth of about 6 feet or so, and wild rice covering about 80% of it. We had spectacular hunting, and at no time did I feel under gunned. When I did my part, the teal and mallards rained from the sky.
I never hunted ducks with a 20 after that day, and never hunted ducks again after steel became mandatory.


Best,
Ted