[cosmicfish]

I started off talking about what could be obtained, it has to be balanced against what is required. Let's start by looking at different team needs:

MARS

As the "military" of the Project, MARS teams need heavy weapons and armor. Presumably they need the ability to withstand .50cal across the board, and heavier for many teams, although they will rely more on mobility than armor. They will likewise need the ability to take out typical military targets from tanks to aircraft.

Recon

Less engaged than MARS, but still expected to engage with hostile forces (to assist MARS and because it is their job to find them), Recon teams need the ability to withstand small arms fire up to and including 7.62 NATO (lots of those in private hands) and preferably up to .50cal across the board, but really they should run from anything bigger. Some heavy weapons would be useful so that they can take out isolated vehicles and hardened positions without needed to call in a MARS team.

Science, Base staff,...

... and other "high value" assets. Supposed to run or bunker down, but they are likely to be slow and cumbersome and need to be able to protect themselves. Protection to .50cal seems appropriate as a minimum, considering the value, but weaponry does not need to match.

Remember that base personnel are not likely to have much of a perimeter, and depending on the base likely lack extensive defenses, so what vehicles they DO have need to be bug-out vehicles, able to depart under fire.

Specialty

MARS and Recon should clear areas of "high risk" opponents before Specialty enters, but they are likely to need protection to 7.62 NATO regardless and may need more - the Project will NOT have the manpower to secure borders!

As far as those protection levels go, it is worthwhile to note that it needs to be durable - many armored vehicles are considered disposable after even modest damage, the Project can't do that. One alternative is over-armoring - something that can shrug off small amounts of .50cal fire can probably shrug off small arms all day long.