I don't have my article nearby but when I wrote "What Happened to the Dictator?" and published it in The Artilleryman ca. 1987, I included a table showing data on well over 100 US 13-inch mortars, M1861. There were at least a couple of founders making them, certainly Ft. Pitt, but as I recall also SMM & Co. Will have to dig out the data. There were enough of them around that many of the tubes remained un-issued at arsenals until after the CW. I'm guessing that mortar bed construction lagged behind tube casting, a possible reason many remained un-issued, but I don't have any data to back that up. All the info on the number made came from the US National Archives, Washington DC, Record Group 156 (Army) and Record Group 74 (Navy.) Abe Lincoln gave the Navy priority for issue of the mortars early in the War so many intended for issue to the Army went instead to the Navy. The records I found showed the name of the ship or river supply base to which each Navy mortar was issued. I seem to recall that many intended for mortar barges were sent to Cairo, IL. The mortar schooners got one mortar each, and mortar barges carried what, four each?