This one was new to me, AustroHungarian experiment. I can't imagine tring to reloading those mausers!
ten Mauser C96 semiauto-pistol gunner "battery" tested -it seems- by the Austro-Hungarians during WW1. Sometime before the end of 1918: that tubular ring turret was fitted to all two-seaters until then. It was replaced later by wooden gun rings. The aircraft is hard to identify; to me it looks like a Brandenburg C.I, but don't take my word for it. The C.I (type LDD) was a very effective single-engine recon aircraft designed by a young Ernst Heinkel and produced in considerable numbers in Austro-Hungary.
Source https://i.redd.it/i1wfeo3bve631.jpg