There are still a few punt gunners in the U.K. One book that gives a lot about the sport is The Complete Wilfowler by Stanley Duncan and Guy Thorn. First editions are hard come by but it has been reprinted. Lagopus.....
In 1987 I picked up a copy of this book in a used book store in the French Quarter, Shanghai, China. It was an interesting store, full of books from past foreigners who had lived in Shanghai during its heyday.
I remember in about the same year seeing a Chinese man with a single break action shotgun with a barrel length way over 4 feet huntng ducks on the Yongjiang river just outside Ningbo (Ningbo is a days train ride south of Shanghai). I have no idea what guage it might have been. The ducks as I recall were widgeon and teal.