Not bad at all. I had a similar sort of idea to offer a set of real, at-the-time-cutting-edge weapons (G36, Abakan, etc.) that a force like XCOM might plausibly use given the time period, before moving onto fictional weapons.
Basic autocannon could probably just be called a grenade launcher. Depends on if you're keeping the AP round or not - if you do, maybe make it a big ol' shotgun shell? Assuming you don't make seperate shotguns. The new rocket launcher looks much better than the old one, too.
The lasers still look like a mash-up mess, though. I'd stick to the silver-and-red scheme rather than mixing up parts. Maybe replace the tan with black if you want some colour variance? Then it looks like polymer/plastic material, which might make more sense for grips/stocks/etc.
Also not entirely sold on the mag placement for the heavy/thermal rifles, although that's a pretty damn cunning use of the old heavy cannon base.
Other than that, everything looks solid and consistent. Some fine-quality spritework, esp. on the gauss and particle weapon sets.
