H. F. Mann, mystery solved! I just figured out how to mount his big one. An extra set of trunnions at right angles would be just the ticket, with off-set sights, of course.
Tracy and Mike
And you guys thought the old Infantryman was nuts for suggesting an extra set of trunnions for H. F. Mann's 8" Breechloader right? After snooping around on the Company of Military Historian's archives, I came across this photo from a John Morris quest to I.D. Breechloading cannon. This is one of John's photo's of the Brayton Breechloader, Model 1861. I think Mann could have profited from an association with Mr. George Brayton.
M&T
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That's the one I was thinking about. I also remember seeing a scale model barrel with the arms attached to the side trunnions.