Damage calculation - melindil/FTSE GitHub Wiki

The following calculations are performed for any single attack, and each individual hit of a burst attack:

Select a random number between minimum damage, and maximum damage - 1 (it appears to not be possible to ever do the max damage of a weapon)
Multiply damage by multipliers for critical hit effect and 1 + ammo damage rating, and round damage down to an integer value
Multiply target's damage threshold by (1 - ammo penetration), round down to an integer value, and subtract this from the damage roll
Calculate effective damage resistance: 1 - (target's resistance * (1 - ammo penetration) / 100)
Multiply damage roll by effective damage resistance and round down
Multiply by damage factor from weapon mode and round down

Once damage from all hits (single or burst) are added, apply the following to the total:

If damage type is electrical, multiply by 0.5 if target is living, and 1.5 if target is mechanical. Round down result.
Add +5 if attacker has Living Anatomy perk, and target is living
Apply attacker's Bonus Damage rating (as a multiplier: 1 + rating/100) and round down
Multiply damage by 1.15 if attack type is Unarmed and the attacker has Bonus H2H Attacks perk (note that this is probably a bug - should be Bonus H2H Damage), and round down
If attacker has Silent Death perk, is behind target and sneaking, and using Unarmed, double the damage
Multiply damage for difficulty. If attacker is a player, multiply by 1.429, 0.769, or 0.5 for easy, hard, or insane difficulty. If target is a player, multiply by 0.7, 1.3, or 2.0 for easy, hard, or insane difficulty.