It is not as well known as it is a less common occurrence since the 16ga is not normally shot in any of the regular Clays games, but Yes a 28 ga shell will lodge in the forcing cone of a 16 gauge gun, same as will a 20 in a 12.
From the appearance of the chamber, I would guess it has been lengthened & not an expert job by any means. I seriously doubt though that was the cause of the burst. Wile the 2 9/16" was standard for the 16 in that era American Guns were not universally marked for chamber length & were available "On Order" in several different lengths. As I recall in 16 they could be ordered in 2 9/16",
2 3/4", 2 7/8", 3" as well as 3Ľ". In many cases, A "Long cone" generally means at least the cone has been lengthened & often the chamber as well. it truly is anyone's guess as to what the original chamber length was. Many chambers, however, were lengthened with reamers having standard cones prior to the long cone becoming popular.
