Sad German Hunting Guns forum is tem down now.
They have an exellent article about his hunting weapons. From a German hunt magazin/ book from 1913. It states he has a Springer carbine 11,15 mm among his many.
That Spandau rifle is 1 of 3 , one of them is in 6x57 caliber. German trial rifle for millitsry trials,not adopted. About 30 made.
Mauser 98 won the conract.
Decades later Gehmann saw potential in Spandau rifle and simplified barrel swap for it. ( not so an armorer could only change it, but you your self also) the m66 was then born.