I have read in several places (And now here) about some Mauser
rifles shooting high,low, way off etc.
In my research I have found that some of the survivors of
forced labor camps during the "Adolf Years" would deliberately
sabotage the sights on firearms they made.
They would leave the front sight step too high or cut the rear notch
a bit deep or off center, or my favorite, don't cut a notch for the 100 or 200 meter mark on the rear sight making precise shooting next to impossible since you are actually set to shoot at 300 meters when you
think you are at 100.
In the middle to late WWII years, German soldiers were not as well
trained as those at the beginning of the war and they simply did not
notice the problems.
I actually have 2 of these mauser sights that
were "Modified" in this way.
A bit of "Resistance work" going on that the Germans never caught onto,
you have to admire the spirit of those prisoners.
