@a63nt-5m1th For future reference, my sweat spot to one headshot protection with DefaultArmour seems to be between 14100.0 and 14900.0.
I'll try using Locational Damage & Deadly Headshots after it !
EDIT :
Locational Damage & Deadly Headshots didn't seem to have an effect with so much armor. I'll seek more into it.
I've realised there is some headshot damage modifiers in weapons.meta, but the base damage and multipliers do not seem to match with my health/armor values.
EDIT 2 :
---- FIXED HEALTH and ONE HEADSHOT HELMET PROTECTION ----
Because having '14000.0' points of armor seems far from being realistic for me
I've changed the weapons.meta/ HeadShotDamageModifierAI value= of each weapons, from '1000.0' to '10.0',
And scaled the pedhealth.meta/ DefaultArmour value= with the same multiplier : from ~'14000.0' to '140.0'.
All of this making them still resist to one headshot bullet, and at the same time killable without headshots. Fits better a more realistic damage.