According to Donald Canney's The Old Steam Navy, New Ironside's original armament was to be sixteen IX-inch Dahlgrens on the gundeck and two 150-pdr rifles on the spar deck. They changed it to fourteen XI-inch Dahlgrens instead, which freed up two gundeck broadside spots for the Parrott rifles. Retouched photos from the era show eight open gunports on either side too, and nothing prominent in a chase location on the spar deck. The segment of New Ironside's gundeck diagram that is in the book (which shows the forward three pairs of broadside guns and rails) shows a Parrott in the number 2 port on the starboard side, sandwiched between XI-inch Dahlgrens fore and aft. Drawing is from RG 74, Bureau of Ordnance, no. 1206 in the National Archives. Canney doesn't make any mention of 100-pdr or 50-pdr Parrotts. The latter isn't a standard Parrott size, that was 60-pdr even in Naval form, though the shell was 50 pounds. 50-pdr was a standard Dahlgren rifle size though, but I don't see them fitting those.
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