in game issue

there is major problem for me didnt face it in the beta or the firt day 

many time i empty half mag on player to kill him but most of them kill me instantly 

i shot player from the back he turned and killed me instantly happened to me alot 

i ads and shot running players they shot and kill me instantly 

they are not hackers but its serve issue or ping or net coding i dont know it ruined my gameplay and the preorder i feel regret cause this problems werent in the beta