There is a large gap between 98 and 100 Health. Two hits with a rifle to the torso for 98, and three hits for 100. Who know that a very tiny scratch to health could make a difference.
The way I see it, there should be a small deviation in the damage dealt by guns. This would make their action a tad bit more unpredictable. A ±5 randomization should be fit for this.
They could also implement damage drop over a distance.
-0 to +5 at point blank
-1 to +4
-2 to +3
-3 to +2
-4 to +1
-5 to +0 at fog distance
Of course, rifle headshots should always be a one-hit kill. Probably increase base damage to 105.
EDIT: In addition, this would discourage sniping with the SMG at fog range, making is a far less efficient weapon at long-distance combat.