Hey, I missed the beginning of a new AR. That's not supposed to happen! You should announce it and provide a link in the AR Discord.
Wow, no love for the M-16? How does one acquire an unreliable M-16, anyway? You'd have to go fetch some of the bad ammo and the original guns tested in Vietnam, and then mistreat the things pretty badly. And why does it use the 20 round mags that pretty much zero militaries use? It's like you wanted us to start with a weapon unsuitable even for fighting a war with a regular old modern military, instead of one unsuitable merely for fighting a war with a spacefaring alien race.
Anyway, Tavor is OK, at least. We should've gone ahead and gotten ourselves a Remington ACR, the new 6.8mm rifle in development for the US military. We'd have to make it work since it presently isn't good enough to replace the M-16, but then this is an Arms Race. The higher caliber would've let us pack a bigger punch, and I believe the ACR is supposed to come in SAW, DMR, and regular AR formats all in one package (using some interchangeable parts).
For now, we definitely ought to give several Tavors to our soldiers, since the extra firepower of the underbarrel GLs ought to make up for our lack of any quality military equipment whatsoever.
Acquisitions Plan Alpha (1): UristMcRiley | http://www.bay12forums.com/smf/index.php?topic=176293.msg8137337#msg8137337
Buying 5 Tavors (1): The Canadian kitten
Alpha Mike Foxtrot (1): SC777
On the subject of mechanics: Having played many ARs, I would not recommend the three-dice system. It is basically tripling your design's chances for failure without providing any serious benefit---it cripples innovation. A 6 in "Complications" or "Cost" would not, like a 6 (or whatever die you're rolling, 2d4 or 2d6 is standard right now in ARs because it provides a more balanced set of results, weighted towards the middle of the range of possible values) in "Effectiveness", improve the result. However, a 1 in Complications or Cost can sink an otherwise good design just as effectively as a 1 in "Effectiveness", i.e. triple the possibility of failure for any given project.
I do agree with Shadow that you don't need so many phases. It works just as well to have an Intercept Phase, an Operations Phase, and a Design Phase (+ revision phase?). Operations is where you purchase all your equipment AND submit a plan that deploys ground troops to each UFO site, since the two things are directly related, while Intercept is where you go shoot down UFOs.
"Research" seems like it's something we'll get to after acquiring some alien artifacts, I guess? Anyway, that seems to suggest you have no Revision phase. I highly recommend a revision phase, it's always good for players to have a way to try and fix a problem with a given design without needing to spend a whole other design action on it, ESPECIALLY if said design action carries the risk of rolling a 1 in just one of the THREE categories and having that sink the new attempt. (If you can't tell, I am not a fan of the 3-dice system and am glad it's gone from newer ARs)
Sorry for the text wall. I realized that this was getting to be a long-winded thing a little too late and I really do want to mention all of those things that fell out of favor after the AR you're drawing a lot of inspiration from. These XCOM ARs are a lot of fun, and I really want to see one of them keep going.