Aimbot.  Check his overall HSKR http://prntscr.com/g0sjr4

And then there's these gems...

65:1, at least 57 headshots, 44 of the 65 kills were with the F2000: http://battlelog.battlefield.com/bf4/battlereport/show/1/889553118186851328/1020928401/

68:5, >=63HS, using mix of AR and PDW: http://battlelog.battlefield.com/bf4/battlereport/show/1/889563151238843392/1020928401/

And many others