ssg69 piv

Hi guys, I recently bought an ssg69 PIV with the 16 inch barrel. I put a swarovski z5 3.5-18 on it. Also mounted using 1 inch steyr rings. Scope has 58 inches of elev adjustment but is running out past 400m when I am shooting. Can anyone shed some light on this, is it no good past 400m ? Or...