That William Read at Cabela's is hardly a "punt gun"!! It is far too nice. It is really just a big old fowler. Punt guns were by an large pretty crude devices, as the one pictured with the two gents holding it.
Sneider in Baltimore made at least one 4-gauge double barrel hammerless shot gun. It was displayed by the Southern California Arms Collectors Association in their display at the 1987 NRA Convention in Reno. It had 38-inch Damascus barrels and weighed 28 1/2 pounds. It would take a man like Destry to swing that fowler.