Like eightbore, I never got around to reading this thread until he "resurrected" it the other day.
Growing up in the South, and on a farm surrounded by plantations owned by well heeled gents, I saw firsthand a good many small gauge doubles that were used by bird hunters. Almost all were bought by a "financially comfortable" father and given to his son, or grandson, for quail and doves. My long gone quail hunting buddy from Augusta, who was about 40 years my senior, used a graded Parker that his father purchased at Maxwell Hardware on Broad Street and gave to him as a boy. He was still shooting it in his eighties, and would use no other. His very unselfish son buried Mr. Tom with his briar britches on and his Parker 20 by his side. There was not a place on that gun where the metal was not bright white from carrying.
Men shot 12's for ducks and turkeys, 16's for quail and doves. The men who used a 20 were the kind who grew up with it, as Mr. Tom did, and just continued to use it for birds, but they were few and far between. The only .410's used by men were in a boat as a snake gun. Boys grew up carrying them, but looked forward to the day they could graduate to a 20 or 16.
My first gun was a .410 double, then a 20, and on my 16th birthday a 12. That was a typical progression around heah'.
Stan