Are perk modifiers to weapon damage added before or after DT is applied?

Solution 1:

Perk modifiers are added before DT is applied.

I decided to do some basic testing in game using the console to add/remove perks and adjust skill levels. The Fallout wiki I linked in my question contains the wrong formula. However the GECK wiki seems to agree with my findings:

Gun Damage = (PerkModifiers(BaseWeaponDamage * DamageMultiplier * GunConditionPenalty * SkillBonus) + CriticalDamageBonus) - DamageAbsorbedByArmor

My testing showed that:

• Weapon condition and skill is applied to the base damage of the weapon first.
• Then crit damage is added (if it was a critical hit) applying the perk bonus from better criticals only to the crit portion of the damage.
• Then perks are applied
• Finally DT is applied