>>269079793
You're retarded and he isn't cheating.
The ak47 is an instant headshot at any range.
It's got a much slower rate of fire so if he ever went for body shots against your m4 he would lose every time. 
He's aiming for your head and upper body and one of those bullets is connecting with your head hitbox and killing you. 
You're probably taking chest and upper arm shots too but you don't notice because they're followed by the one clap that matters. 
Load up a small map with bots. Pick the ak47 only aim for the upper body and head and try it for yourself.