Fast ******* deaths in crysis?!?!?!?!?!?!?

I just started playing crysis 2 last night and it seems that i can shoot someone with a whoe clip or two clips of my gun with every hit marker hitting and about one out of ten times does it kill them. why do i get killed with two or three ******* bullets and they're not even headshots?!?!?!?!?!?!?!? I have never been so pissed off at a game before because it seems like any other game i ******* dominate. WTH IS WRONG WITH THIS GAME? any tips????