RE: Mauser 98????
If it's still got the ramp sights and all the #s match, yep should be a 8 x 57, however when in doubt take somewhere and have it checked, the piece of mind will be worth it (a lot of the rifles that came back where also reamed to a 8 x 63 or here abouts a 8-06) and that would be an all matching gun also.