Hey, guys. My friends and I have been looking into issues with taking high damage (one shots) to players in the mission. We've managed to narrow it down to a FAR script. Inside the FAR_revive_funcs.sqf, we altered FAR_HandleDamage_EH. basically changing the if statement, if (alive _unit && _amountOfDamage >= 1 && _isUnconscious == 0) to if (alive _unit && _amountOfDamage >= 0.9 && _isUnconscious == 0 && _bodyPart in ["","head_hit","body","hands","legs"]).
This explains it pretty well...
https://forums.bistudio.com/topic/108931-handledamage-eh-explained-poor-mans-gethit/
Changing this has allowed us to withstand multiple shots from the player and AI as should be. Hope this helps.