i find it quite balanced betwin M4a1 And Ak47 :

M4a1 Costs More Then Ak47 , Making Up For The Higher Dmg

AK47 , On The Other Side , Is Pretty Much Cheap , making for the small dmg and Bein Inaccurate

Most Players Use The Sliencer For The M4a1 , Which Decreases The Dmg A Bit , like one or two dmg decreased