this is a Gew98 this is a very popular sporter conversion of WWI vets bringing rifles home this is also seen on allot of the Gew88 and Kar88 of its time post WWI. beyond local gunsmiths factories like Haenel, Spandau and J.P. Sauer converted rifles as post war work and this is were also the conversion of the 2 or 3 shot bolt action shotguns came about to keep up with the treat of vasilies (wrong spelling). there were many other factories dueing thses to stop them selves from goign bankrupt. Your seems to be a gunsmith conversion as it appears he marked it with his initials. on a side note maybe its just the lighting but it seem they might have torqued the receiver and rail while de-barreling this rifle??