Back in the 40's in Bellingham, WA there was a guy named Lyman Banks. Bellingham is on a flyway for snow geese, Canada geese and lots of ducks. Lyman worked on shotgun barrels to make them better high pass shooting guns using large shot 4's, 3's 2's.
I have a Model 12 3" Heavy duck gun with a Bank's bore in it. I'm not familiar with what the process was. I don't know if he full length bored them or just did choke work. I can tell you that the Model 12 I have was heavily sought after by one guy who borrowed it for a goose hunt. He tried to purchase this gun for years and the man who owned it wouldn't sell to him. I purchased it from him very late in his life, we were friends and partners in a hunting trailer in Eastern, WA.
This barrel on my Model 12 will take a dime through it without touching the inside of the barrel, Current day gun chokes do the same on there overbore barrels.
The guy who started me shooting shotgun when I was 20 used to shoot patterns for Lyman. His name was Terry Cassidy, he used to tell me Lyman would talk him up on how good he was shooting those patterns LOL. Terry in later life said Lyman didn't want to shoot all those patterns with the 3" magnum loads at 1 7/8 oz of 3's and 2's. The guns were patterned at 55 yards and the best pattern we seen in the 80's was with Federal Premium Magnum loads, lead shot with 1 5/8 oz 3" copper plated shot. We later found 1 1/2 oz 2 3/4" same shells shot better than the 3" did, put more pellets in the 30" circle. The highest percentage we ever saw was 55% at 55 yards. It was shot with my Dads Browning Belgium 3" Auto 5 with a Federal Premium lead 1 1/2 oz. of 4's.
PD