A guy here in town killed a deer with a .177 cal air rifle.
Another guy shot a stray dog with a .20 cal Benjamin multi-pump and the pellet passed completely through the chest cavity, killing the dog. Neighbor was very upset.
Deer poachers in the deep south use .22WMR a lot as it is plenty powerful and doesn't make as much noise as a centerfire rifle.
Penetration capability of .22LR 40-grain and heavy pellets from a powerful PCP air rifle in flesh is rather surprising.
My .25 cal PCP rifle shoots Baracuda pellets through 1.5" of pine wood, or 3/4" of plywood. If you put a magnum primer in the mouth of a .25 cal hollowpoint pellet, you will blow a chunk of wood from the backside of the plywood. That's brainshot ammo with shock effect. It will shoot Baracuda pellets through 4 half gallon milk cartons filled with water. Try that with your .223 varmint bullets. Need I say that it will shoot through coyotes?
The special ops .22LR ammo was probably Aguila SSS 60-grain subsonic. It is a military designed round. Fairly quiet without a suppressor. I have several boxes of it. About as loud as my PCP air rifle, but a bit more fpe, even though probably slower out of a long barrel. I see it flying to the target. My CZ 452 isn't fond of it, but my brother-in-law's M77/22 shoots it very well. He doesn't need an air rifle, just a stash of Aguila SSS .22LR.
I have yet to recover a pellet from any varmint I have shot with the .25 cal PCP air rifle.