I've played around with how they use cover at long distances too at the shooting range. They seem to know exactly when you are reloading even if you are like 100m away from them without depleting your entire magazine. They'll pop out of cover the moment you begin to reload even though its near impossible to determing something like that at such a distance.
@pasiaks74 hes saying the ballistics are more realistic in battlefield, not the entire game in general which I have to agree. The hitscan distance is way too far in Sandstorm and BF does do a phenomenal job im mimicking how bullets actually travel irl.