My internet and IMGUR are a real cock up.......... anyones guess day to day if I can get photos posted.

As to “Col. Gordon”; it looks like it well could be “Chinese” Gordon or “Gordon of Khartoum”.....but I lack definitive resources.
Scottish ancestry, British Officers were usually keen sportsmen, a Scottish gunmaker, and a military calibre. Not to mention that I cannot find another “Colonel Gordon” noted in available records of the British Army Officers in exactly 1872
His diaries of that period apparently were published at one time, but are elusive and not so far found online or available in print.
I have sourced a book of his letters to his sister (paperback)....we shall see. I doubt he might have mentioned his sporting arms to his sister, but who knows.
Thus far an enigma.
- Mike

ADDED:
As an interesting (and perhaps controversial) aside; the old .577/.450 MH as in this Henry, with black powder, equals the traditional .375 H&H 300 grain load in Taylor’s KO values..... ~39 for either one. Maybe those old boys were not as under gunned as modern guys would think?