No worries, Mazo. I knew somebody here had one, just couldn't remember who.
I have not been able to find any manufacturer literature or information about this rifle, and what little information I did find on the internet just called it a swivel or rotating breech, so I doubt that's the actual nomenclature used by Numrich. I haven't found any indication it was marketed as an Hopkins & Allen, like several of their other offerings of the same time period - apparently Numrich bought out H&A's tooling and stock, continuing manufacture under license for a few years.
I looked at the forums on the Numrich site, and apparently even they don't have any schematics, load data, quantities or exact dates produced. Numrich still has many replacement parts for the lock, listed as H&A (except the main spring).
What loads have you use in yours? I haven't measured the bore on mine, but what I read indicated Numrich barrels ran a little tight. Does a .440 PRB over 40-60 grains sound about right?