hey, ive noticed this a lot especially when im playing online but, wen u aim down the sites and fire...depending on how far away from the target u are the bullet dosnt go to where u aim.
wen i use the kar 98 i have to aim at the knees to hit the chest sometimes....is this part of the realism and if so can u give any advise so i can improve?

Well, in real life, the bullet does not travel in a straight line. It travels in an arch.
strange that you have to hold low on your target in a video game. In real life a firearm can shoot to the left, to the right, low, or high, or even POA (Point Of Aim). Just a matter of adjusting your sights or just learning where to aim.

This game has a significant gun sway as well as a "cone of fire" that even though a bit overdone..make you utilise your squad to suppress while you flank.