One thing to check..The bullet weight, these and other '98's in 8mm, sights are regulated for what ever bullet weight the goverment of the country wanted. Most common is the 198gr bullet, but some of the surplus ammo being sold is 150gr,and commerical ammo (at least in the U.S.) is pretty weak, using a lighter bullet than the sights are regulated for could cause a POI change.. I also agree with everyone else and I'd set it up at 100 yds or meters, and then try again. I'd also try a 198gr or a 200gr bullet if you aren't already.. Another common problem is the height of the front sight, since there is no way of knowing what has happened to this rifle over the years and who or how often it was rebuilt,it's also very possible that the front sight blade is not of the correct height, with so many Mausers of diffrent types,(rifles carbines,etc) countries manfacturering, being used during WWII. It's very possible your could have the wrong height blade in it.