: Except that you don't actually see that sort of weapon redundancy in real
: life. You see different weapons across different militaries and maybe
: different branches of the same military. It's been established that
: everyone in the UNSC uses the MAV/AW, from ODSTs to Marines to the Army.
: And an organization as large as the UNSC isn't going to drop a
: longstanding design for something that offers the same performance.

There have been countless weapons in the U.S. Armed Forces for the past couple decades that have pretty much been the exact same, or at least had the same role in a slightly or drastically different design. The Mk.16 5.56mm SCAR was slated to replace the M4 in special operations service. It didn't. The M4 is still very much in use, as is the HK416 which differs little from the M4. The amount of different designated marksman rifles and sniper rifles alone is staggering.

There's precedence in the UNSC too. The differences between the MA5 and the MA37 or the M90 and the M45 seem a lot more intricate than aesthetics let on. I would bet that much of the internal workings are distinct from each other despite filling the same role and utilizing the same ammunition.

: The other problem is one of icons. These guns are iconic, they're a part of
: Halo. Furthermore, they have a weird design that sells the universe as a
: science fiction setting. So, if they're going to redesign the assault
: rifle (Replacing the MA5, not retconning it) it had better not look like
: an M16 derivative. If they're going to redesign the pistol, don't make it
: look like it came from the desk of John Moses Browning. And if they're
: redesigning the rocket launcher, the end product shouldn't look like a
: Carl Gustav.

How iconic do you need to be? Sure, this is just fiction, but sell me on a civilization, not a fantasy. Some things are going to look pretty boring and I'm fine with that. I'm sure few can tell me the aesthetic difference between the original Bazooka, the RPG-7, or an M3. More or less, they all look pretty similar. Instead, you call it a rocket launcher, a bazooka, or an RPG. You may not know what they look like for certain, but you have a good idea; a long tube with some sort of firing mechanism like a trigger coupled with a grip that's mounted over someone's shoulder. That's iconic and those weapons are real.

And honestly, Halo's rocket launcher is not that much of a far-fetched design. There have been individual launchers with multiple tubes for decades. Even if that weren't the case it would still be just be like an enlarged version of an MGL like the M32.

: Contrast the shotgun. They're free to redesign the shotgun. They have
: redesigned the shotgun. Nobody gives a flying fornication about the
: shotgun, because it's too generic for anyone to have developed an
: attachment to the design.

Save for the assault rifle, magnum, energy sword, Needler, plasma grenade, plasma rifle, and plasma pistol, I honestly think that there are no iconic weapons beyond those seven. Nothing to make most people jump and scream Halo.