shots to kill?

Why does it feel like the shots required to kill enemies is more than the amount it should be. I dont mean how annoying it is that the guns that say 33 dmg are only 33 dmg for the first 5 feet then it drops off to 20 making it a 5 shot from a 3 shot, but i mean when i blast someone point blank with the galil (33 dmg, 3 shot kill) and hit all my shots before the kill notification comes up i have used like 6-7 rounds not 3. Like is the damage output laggy or do half my shots just not deal any? and about what i said the damage range needs to be extended some of these guns say 3 shots to kill but that quickly falls off to like 20 unless you and the enemy are close enough to kiss its ridiculous.