Toby, you could be right on the subject gun. You have seen and handled many more than I have. I would like to see the standing breech on the gun you picture. I wonder if it has the firing pins installed like the gun in question. Seems like a lot of work to install firing pins this way, when one could just drill them in if it was not a conversion.
Here is another gun done like the gun in question. Guns International has a few Westley Richards hammer centerfires they call conversions. This one calls the gun a pinfire, but of course it is now a centerfire, converted sometime after 1873 with a Deeley and Edge forend, similar to the Amoskeag conversion. Note the breech face is done like the gun from NZ.
http://www.gunsinternational.com/guns-fo...un_id=100858561
