This Is what I wish the Halo Assault Rifle looked like.
It has a rail sight for multiple attachments, Small and versatile, you can actually aim the thing with iron sights that all of the originals lacked for some reason or another.
I made the gun smaller than the original because the UNSC is in space, so Why would the make a big, clunky gun to be used in the tight corridors of space ships (halo 1) or give it a "shell" on the top so that it does not have any way to actually aim it without the inclusion of an assisted targeting reticle.
I also Beefed up the Magazine so that it realistically hold 60 rounds.
I'm done gripping now, Enjoy!