None of your points are related to the fact that a gun in which the receiver is not aligned with the barrel physically CANNOT work. Everything in Halo was explained in some way, and from a functional standpoint, was realistic. A gun without sights is realistic. It's "accurate" in the game because you're a super-soldier with a fancy suit that interfaces with the weapon and helps you aim it. Also, the gun is shown to have recoil... all of them are... in all Halo games. The fact that it doesn't bounce your reticule is irrelevant because it's a video game. My point is... you've completely missed the point.