There is a good publication on The Martini Henry.
Its states Quote" The breech-loading, single-shot .458in Martini-Henry rifle has become a symbol of both the Anglo-Zulu War of 1879 and the numerous battles in Egypt and the Sudan in 1884-85, but continued to be used by both British and colonial troops well into the 20th century. Its invention and introduction into British service were in direct response to the success of the Prussian Dreyse needle gun, which demonstrated that the breech-loading rifle offered faster loading, improved accuracy and superior range; significantly, the weapon could be loaded and fired from a prone position, thus offering the rifleman greater security on the battlefield. Due to the longevity of service, many Martini-Henry rifles survive today, both in museums and in private collections, and the weapon is highly prized by shooting enthusiasts. Featuring specially commissioned full-colour artwork and an array of arresting first-hand accounts and written by an authority on warfare in the Victorian era, this engaging study tells the story of the powerful Martini-Henry and its impact on the battlefield, from the Anglo-Zulu War to the opening months of World War I."Unquote.
There is a very substantial preview at https://books.google.com.om/books?i...20hENRY&f=false