Machinegun bullets shouldn't do jack to a fully armoured head.
Sets armour hits to the head to only cause pilot injuries if the damage does 10 damage or more in a single instance.
Sets structure hits to the head to only cause head injuries if the damage does 5 damage or more in a single instance.
The above settings are customizable in the mod.json file.
This mod can turn out academic if it's something like an assault mech's AC/20 that manages to score a head hit on your mech.
Place the mod folder inside the game's mod folder:
WIN: C:\Users\user_name\MyDocuments\MyGames\BattleTech\mods LIN: /home/user_name/MyGames/BattleTech/mods OSX: /Users/user_name/MyGames/BattleTech/mods
If the above folder doesn't exist, you need to start Battletech to have it create the folder.
If you get a message about needing to overwrite the folder, click yes: either you're updating the mod (in which case you should be replacing it), or you're installing another mod from me, in which case your OS should be smart enough to merge the conflicting folders.