This may sound pretty simple, but I'm a pretty simple guy. I always thought some of the major differences in field carriages versus naval carriages had to do with their environment during use. When I was on the gun deck of the USS Constitution, I was struck by the cramped quarters and lack of vertical clearance. You need a low carriage. Further, the naval carriage needs to be securef very well, as we all know the origin of the term "loose cannon." The naval carriage spends its life in the same confined twentu square feet, while the field gun is always on the move. And given the close quarters combat prevalent in the 1700's and 1800's, a quoin seems more expedient than an elevation screw. As I said, I'm pretty simple.