AI Damage is really bad, much worse than Arma 1 or 2.
If you use noise supressor in your weapon, enemy AI could eat 8 or more shots before die. It has not sense.
In Arma 2, a couple of shots in the leg and the enemy had to lie down, one or two shots in the chest... enemy down. 7.62 mm and 1 shot 1 kill.
Also, enemy always knows where are you, although you are hidden behind a wall or a rock.