There is a really good article in the May issue of the American Rifleman on 1700-1800 civilian smoothbores. Great pics of original fowlers, fusils, trade guns, ect. from both sides, and from top and bottom. Impressive bore sizes, from .62 (20 gauge) to .82 (about 8 gauge). They talk about the surviving molds for these guns capable of casting both buckshot and ball, and their use as hunting weapons by the early colonists. Worth borrowing or stealing the mag if you don't get it.
(Are you not an NRA member? if you own a gun you should be!)