Nope. Long range shooting requires raising the backsight, not the foresight.
The usual problem with ex-service rifles is getting the POI down at short ranges. Many were "zeroed" for 200-300 meters. and at 100 meters will shoot way above the black, even with the backsight leaf set as low as it will go. Which is why everything "Mauserish" that I have has ended up with an extra tall foresight blade. From M1871 through to the Israeli, they all took the same type of blade. My Swede and Swissas well (different types of blade, of course).
I think it is more likely that - apart from defects, such as bent barrel, bad crown, bullet/bore mismatch etc - the rifle was rebarreled for target shooting and the previous owner deliberately fitted a tall foresight blade to get the backsight leaf setting well off the floor at 100 meters and have some leeway for adjustment to suit different types of ammunition.
But treat yourself and the rifle to at least one pack of good modern ammo. It is not a fair test of the rifle to use milsurp ammo. If you can find a pack of the Norma RussianMatch, you may see spectacularly different results!