So I've had some reaction fire friendly fire and lost one of my troops because of it. The Rifle was attempting to reaction fire against a zombie on the upper floor of the building to the left, hitting my soldier and dealing a whooping 113 damage.
Now initially I wanted to file a bug report but I'd like to understand how this works first. The MAG Rifle deals 105 average damage or 157.5 maximum damage (150%) and has no armor mitigation, meaning the Sentinel should have reduced damage taken by 60, meaning the killed soldier should have taken at most 97 damage, 16 less than what he actually took. But if there's a 10% bonus against humans (like you get when analyzing aliens) then it adds up: 157.5 * 1.1 = 173.25, minus 60 = 113, the amount of damage taken.
So, is there a damage bonus when attacking humans? Or is it some armor bug? Occasionally I felt like the armor doesn't work properly if the hit unit isn't specifically targeted, but that's a bit iffy.