Does your rifle show proofmarks like these? These are the proofmarks introduced July 23,1893 as special markings for proofing rifles chambered for the M88 cartridge, aka 8x57I with the 4000atm proof cartridge.

Mostlikely your rifle was built on a Mauser, Oberndorf commercial action. The set trigger mounted directly to the triggerguard is evidence. Prior to WW1 anyone wanting to build a M98 action rifle had to buy a commercial action from Mauser first, as there were no surplus actions and the Mauser patents were still valid. Mauser then sold about two thirds of their commercial production as actions only to other gunmakers. These actions were not "Mauser"-marked, but are easily identified and dated by the Mauser commercial serial numbers found under the receiver ring and on the rear wall of the magazine box.
You also mention an eagle stamp on the barrel. Does it look like this one?

This eagle is a military acceptance stamp applied by the Prussian Spandau arsenal in 1915. During the first part of WW1 many scoped sporting rifles volunteered and soldiered as stop-gap sniping rifles. As such, they are not only fine sporting rifles, but pieces of military history as well, as these were the first modern scoped rifles used for sniping. Wrote an article about these now rare militarized sporters in "Waidmannsheil # 47", a publication of the German Gun Collectors Ass., www.germanguns.com .