I have a very close copy of this piece, an Oberndorf Mauser, serial # 79XXX, confirmed to have been made in 1912. Mine does not have the fancy etching on the trigger guard and floorplate, nor does it have a scope mounted though it is bored for a scope. I have no idea if this boring was done at Oberndorf or by the GI who brought it back (This "Bringback" I have documented somewhat).The bolt handle is slightly different, as is the stock checkering, but like the photos posted mine also has the very slight "schwaubles" just foward of the rear sight and at the muzzle.(Yea, I know, I didn't spell that correctly!)
My piece is a .318cal which is smaller than a standard 8mm, and I have yet to get the chamber cast for proper brass size. This may also be your situation, so possibly caution is in order before you fire it....or maybe I'm worrying unnecessarily???