Here's what I got from someone in the know.
The discussion about Kropatschek and others is all b...s...!
It is a single shot stalking rifle built on a German M88 "Commission Rifle" action, the protuding and offending magazine replaced with a more "sporting" triggerguard. Such single shot conversions of M88 actions are not as rare as you may think. Many hunters pre-WW1 did not like the clumsy repeaters, useable only with the M88 packet clip, but wanted a slim stalking rifle for one of the "new high speed" smokeless cartridges without spending much money on a break-open or falling block rifle