You indicated you logged in to the Henry records. I didn't know they were available on line. Do they show the actual ledger page or a text version of the information. I believe that John Dickson & Sons are the custodians of the Alex Henry records. They charge for copies of the ledger pages. https://www.john-dickson.com/gun-history

It might be important because during that period there was another Charles Gordon (Charles Ferrier Gordon born 1859 of Halmyre Scotland) who was an active buyer of high quality firearms. He bought so many guns from John Dickson & Sons it was mused that the company would have gone broke without him. So the question is, does the actual ledger page record Colonel Charles Gordon or simply Charles Gordon which a later transcriber has assumed to be Col Gordon? Interesting it is thought that Charles Ferrier Gordon made his first purchase in 1875, therefore your odds are more favourable that an 1872 purchase was the Colonel Charles Gordon.

Either way you have a beautiful rifle irrespective of its provenance.