When an AI unit has only one magazine/box/missile for any weapon he has, or he has no magazine/box/missile left, he says "No ammo" in either case.

One of the problems is that he doesn't state exactly what magazine/box/missile for what weapon he has only one left. He even says "No ammo" for a weapon he is manning at the time (in the case of AMV-7 Marshall, he says so if it's the machinegun he has used all ammo of, and doesn't if it is the cannon), to make it more vague.

The second problem is that it doesn't clarify whether he has only one magazine/box/missile left or he has completely used up all of them.
This is obviously bad in many situations. If he is talking about the AT launcher he's carrying, having one missile and none is very different. If he is talking about the HMG he's manning, having 50 rounds (which is where he starts saying "No ammo" rather than "Low ammo"), and 0 round is pretty different.
It only makes slight sense if he is talking about his assault rifle, because you, as the team leader, cannot consider him combat-capable even if he has 1 magazine left.

The third problem is that units with "No ammo" always reply first to the leading player's "All, report status" command. This is more confusing to the player than it is helpful, because you are issuing the command, expecting the unit with the smallest number to be the first to reply.
It's not helpful to make the ones with "No ammo" to reply first, since you've already heard that they have "No ammo", when they reached that status, too.

The fourth problem is that, in some situations, the AI unit says "No ammo" even if he has plenty of magazines. For example, if he has a MX SW and only one 100-round magazine left, he says "No ammo" even though he has many 30-round magazines. Surely, having 100-round magazines and 30-round magazines are different, but not different enough to warrant saying "No ammo".

The solution I suggest is to make it specify the weapon type and the ammunition type, and not make them reply to the "All, report status" before the ones with smaller numbers reply.

Example of the suggested radio protocol:
3: "Last 100-round mag on my MX SW."
1: "All, report status."
2: "Grid: 0160555."
3: "Last 100-round mag on my MX SW."
3: "Grid: 0160554."
4: "No missile left for my Titan."
4: "Grid: 0160553."

Example of the current radio protocol:
3: "No ammo."
1: "All, report status."
3: "No ammo."
4: "No ammo.
2: "Grid: 0160555."
3: "Grid: 0160554."
4: "Grid: 0160553."