Weapon Spread (Fallout 3)



Weapons spread determines the accuracy of a ranged weapon in degrees. Formulas here were taken from the GECK wiki.

Spread computation
$$\begin{align}\text{total spread} = \text{aim spread} + \text{weapon spread}\end{align}$$

The total spread is equal to the sum of the spread due to the character aiming and the spread due to the weapon itself.

Aim Spread
$$\begin{align}\text{aim spread} = \text{perk effects } ( & \text{state effects} * \text{skill effect} + \text{limb condition effect} ) \end{align}$$

State Effects
State effects combine multiplicatively.


 * Crouching reduces spread by 40%. (multiplier: 0.6)
 * Using iron sights reduces spread by 65%. (multiplier: 0.35)

Skill Effect
The appropriate skill (Guns, Energy Weapons or Explosives) reduces spread by 0.5% (from 50% up to 100%) per skill point. (multiplier: from 0.5 to 0)

Limb Condition Effect
Damage to limbs increases (pre-perk) spread.


 * ArmPenalty is 0 with no crippled arms. 0.5 when right arm crippled with one handed weapon, 0.25 when one arm crippled with two-handed weapon, 0.5 when both arms crippled with two-handed weapon.

Weapon spread
Weapon spread is equal to the Min Spread stat of the weapon in degrees. The weapon condition has no effect on spread.

Bugs
Prior to patch 1.4.0.525, ammunition that had a spread modification effect (like the 12 gauge shotgun shell) applied it to the aim spread instead of the weapon spread.