I also found that at any range but pointblank, it’s awful hard for ME to hit anything, but enemies I never see wax me easily. I don’t know if a sniper was just acing me or if something else was going on.
I do know (from wargames in the real Army when I was in) that often in real life you get killed just like that-and never saw what hit you. I can say that you respawn fairly quickly, which greatly lessens the frustration for newbies like self. But be careful: in some games, reinforcements are limited. Again, that’s realistic.