I also made it to Salem, Massachusetts a couple weeks ago (February 1).
I took these in front of the "Peabody Museum", which is located a block behind the "Salem Beer Works".
The is the left side of one gun... a carronade on a naval-style carrage)
This is the right side of a second one (matching pair it seems)
A front view of one of them... poor photography at almost midnight, but the sides of the carriage are not parallel...it is wider in the back than it is in the front... and the rear wheels are spaced farther apart than the front wheels are.