I've found no confirmation of its arrival at Baltimore, no any information regarding the substitution of the Parrott rifle for the 12-inch Columbiad.
NAUGATUCK was eventually armed (for main battery) with one 100-pounder Parrott rifle, which exploded while firing during an attack on Richmond, VA, on the James River.
There is extensive correspondence in the National Archives RG156 Entry 6 vol. 22, and entry 3, vol. 54 and 55 regarding the armament to be provided to the vessel and shipment status, however nothing mentions receipt of the 12-inch Columbiad, nor anything about the 100 pounder Parrott.
The many telegrams/letters on file, all dated 22-26 March 1862, include items from Rodman to Ripley, Ripley to Rodman, and Ripley to the Collector at Baltimore.
The last-dated item found is a telegram from Ripley to Rodman dated March 26, 1862: "Where is the 12-inch gun now? By what route has it been or will it be shipped to Baltimore, and when will it reach there?"
Where can I find any telegrams or letters sent by the Collector at Baltimore during this brief period? I think that would answer the question of what happened to the 12-inch Columbiad and why the 100-pounder Parrott was substituted for it.