I really hope they have some better guns in the pipeline for this game, because the three we've been shown so far in these posts aren't at all grounded and have lost the aesthetic of the movies.
"L" is a British designation. If the Colonial Marines are a US organization, the L for the L56A3 would be dropped for a different designation. The US has adopted British designs before, and they all were given different names. The whole "metamaterials" thing is bullshit and not even the correct use for the term. Making things lighter doesn't make them better or more effective, and there's only so light you can go before the gun isn't functional. It's a lazy attempt to sound technical and futuristic.
What exactly does the Volcan's post mean by "an arm?" An actual human arm, or something similar to the smartgun's Steadicam arm? The vagueness is pointless here. If this thing is supposed to be tied to your arm, it won't be as effective as the M240. Why? In order to have adequate fuel and range, the Volcan would have to be large and heavy--too heavy for the human arm to handle. It's impractical, and inferior to the M240 and most flamethrowers used today. It would make more sense if "an arm" means a Steadicam arm.
The Type 78 is bullshit, lazily designed, and should go back to Halo. All handguns are technically bullpup, so this just shows no research was done. It doesn't even look like it can be properly held.
I still have hope for this game, but I don't understand why the developers didn't stick with the film's aesthetic, or do some research on how guns actually function. "Make things 'cooler'" is a sad trap that FPS games need to pull themselves out of, otherwise all we have are Halo/Star Wars/Mass Effect clones.