I thought I would also mention that I recently picked up a book called "GERMAN MILITARY RIFLES FROM THE WERDER RIFLE TO THE M/71.84 RIFLE" by Dr. Dieter Storz. It is a ~ 500 page book that goes into detail on the Mauser 1871 development and actually goes into deep detail surrounding the Gewehr 71.84, which as a fellow CGNer has mentioned, has very little documented data elsewhere.
I picked it up from a trusted book shop in the U.S. for $140 CDN shipped to my door and I don't regret it for a moment.