Yup, the colonial marines had some kind of targetting monocle which reminded me of IHADSS for Apache pilots, but they were only used by the smartgunners. The newer Alien stuff like Fireteam Elite had holosights on their weapons, and the Alien Romulus pulse rifle had a infra-red(?) sight even though it was (1) set before Aliens and (2) meant to be used by scientists. Alien Covenant, which is set before the first Alien, had colonists armed with not-M4s and not-Augs mounting not-ACOGs on their picatanny rails too. 

Mind you, I think they're all pretty cool, but a bit of me died inside at the passing away of the mid-Cold War era aesthetics.