Chirons have 12 ammo. Once they ran out of ammo, that’s it - often they will just run away from the map.
On regular stance they shoot 3 projectiles (50 dmg, 3 shred each), too imprecise to reliably hit the same target twice.
Using stability stance they can shoot 5 projectiles with greater precision, but getting in and out of stability stance costs 1 AP, which means they can’t move and shoot.
The range of Chirons is actually 40 tiles: only 2 tiles more than a GL with Biggest Booms (25 + 13) (this is useful if you want to get an idea of whether you are within range of a Chiron without having to count the 40 tiles). Lairs are at least 60-70 (maybe more?) tiles in width and length.
Chirons only shoot at detected targets, and they tend to prioritize targets that are closer to them. Stuff like spider drones, turrets or decoys are like magnets for their projectiles.
Their heads are completely unarmored, and when disabled their WPs are reduced to 10.
As they need 3 AP to shoot, a single casting of warcry is enough to put them out of action for one turn.
I could go on and on, but there is plenty to do depending on each situation. I just finished a playthrough where I regularly had explosive and acid Chirons to deal with (and that without making use of extreme mobility, or skill spamming, etc.).
Yesterday I actually did another Lair with 2 explosive Chirons on a map “without cover” (that is, without the egg-like buildings), where one of the Chirons is walled off, so there is no direct LOS at it from low ground.
But it is located near the right edge of the map - the spawnery being in the top left corner and the exfil top center.
The other Chiron is near the Spawnery behind elevated ground. So on that precise map all you have to do is stay undetected while you cross the only point in range of the walled Chiron, hug the elevated ground from the opposite side of the other Chiron so that it can’t shoot you, and take it out close range next turn.
Can there be situations where you can’t deal with 2 explosives Chirons with stability stance on a map with no cover and no immediate LOS to the Chirons? It is possible, depending on map, number & strength and deployment of other enemies, and, of course, the composition of your own team. But it’s far from accurate that this is so as a general rule.
EDIT: uploaded pics, corrected dmg per projectile