There is no M4 and no H&K 416 assault rifle in game unless you mod. I know this is based in 2035,but the MX (ACR) M4, H&K 416, and the m320 Sniper rifle (CheyTac M200 Intervention) are all present day weapons but the m4 and 416 are not in game (yet).
Currently those weapons are only available via modding. {F20641} {F20642} {F20643} {F20644}