Shawn- I'm looking for items along your line of enquiry, also. Ft. Pitt and Frankfort Arsenal are the places I'm searching for records of. These are noticable by their absence. Navy Department records show men detached for short periods of time, by their later service the period in question was -probably- testing and training.
If anyone out there has any detailed information on the design and development of the Model of 1861 XIII inch bore mortar please contact me. It has the level of documentation of a current'Black' operation.