before i start dont look at my rank. this is a new account but i want to know why i cant kill the following players no matter how much i shoot at them

spiitfire
crazyfist
sdub
ultimatecloaker<3
incep7ion
Danuvious

i shoot these players like my bullets are cheese they dont die. i melee and nothing happens...where am i going wrong? i was playing this game from the demo then stopped in november-december and started to play again in february

also, i get killed a lot lately. i shoot at person someone kills me from behind or lately it happens i am facing 3 opponents at once. this aint fair. when i play at other servers where these players are low rankers ive achieved score like 35-7 or 41-9 or even 50-10 but when i play against these guys they just dont die cause not only do they not die a teammate of theirs also shoots at me giving me the disadvantage

ive been playing the game since pretty much from release i cant just accept the fact they have better aim than me and kill me with less bulelts than i them???? playing and playing till i get sick and what??? nothing, they dont die.

and no i am not accusing them of cheating