In borderlands, Weapon Accuracy, also known as Accuracy Rating, Weapon Card Accuracy, or sometimes (more ambiguously) just Accuracy, is a rating of how accurate a weapon is. It describes the deviation of bullets in regards to the body of the weapon. Internally, this rating is quantified as a Spread.
Weapon Card Accuracy and Angle
Each weapon has an accuracy indicator in the form of a percentage, where a higher percentage yields smaller spread. This is an indicator of the angle of the cone in which the gun fires projectiles.
The aperture (angle) of the firing cone is equal to the weapon value "Spread" (in degrees), from which the Accuracy percentage is derived.
- Spread = 12 × (100% − Accuracy)
where Accuracy is the percentage value (e.g. 75% Accuracy → 3 Spread → 3° aperture).
You can convert the spread aperture to an "area" (solid angle) that bullets fire into using the equation
- Area = (64800/π) × (1 − cos(aperture/2)),
where area is measured in square degrees.
- A gun with 98% Accuracy has an aperture of 0.24°, firing into a target area of 0.0452 deg2.
- A gun with 90% Accuracy has an aperture of 1.20°, firing into a target area of 1.13 deg2.
- A gun with 50% Accuracy has an aperture of 6.00°, firing into a target area of 28.3 deg2.
The consequence of this is that gun Accuracy should not be compared as a percentage, but as a distance from 100%. Even though the "first" 5 or so accuracy barely have an impact on actual accuracy, every point is "more valuable" the further it is from 100%.
- A 98% Accuracy (0.0452 deg2) sniper rifle is twice as Accurate as a 97.2% Accuracy (0.0887 deg2) sniper rifle.
- A 91% Accuracy machine gun (0.916 deg2) is 133% more Accurate than an 87% Accuracy machine gun (1.91 deg2).
- A 26% Accuracy shotgun (61.9 deg2) is 43.9% more accurate than an 11% Accuracy shotgun (89.5 deg2).
Internally, Borderlands keeps track of a weapon's accuracy using a metric called "Spread." It is basically the distance of Accuracy to 100%, expressed in degrees. The "back-and-forth" formula is:
- 100% - Accuracy = Spread ÷12
where Accuracy is a percentage. Each weapon category has a "Base Spread" as described in the bellow table.
|Support Machine Gun||2.4||80.0|
|Semi-Automatic Sniper Rifle||0.6||95.0|
|Repeater Sniper Rifle||0.4||96.7|
From there, this base spread can be modified by the parts that make up the weapon, according to the Borderlands stat modifiers mechanics.
When sighted, all weapons will receive a Spread bonus from their Scope: They will literally be more accurate (!) and shoot straighter. Shotguns and Mashers will fire in a tighter pattern when sighted.
The accuracy bonus is quite substantial. What is very interesting to note is that this bonus is not stacked additively to the other Spread Bonuses in other parts: It is applied multiplicative afterwards, as its own stand alone field.
The table bellow also shows the resulting Spread compared to the weapon's unsighted Spread. All weapons will get the same bonuses from their scopes, except for Machine Guns. The actual bonuses are:
As can be seen, a high powered scope can have a substantial effect on the spread of a weapon. This will of course make Sniper Rifles that much more accurate, but it should be kept in mind that inaccurate weapons, such as Matadors or Anarchys will benefit just as much (extending their useful range from point blank to a few meters).
When comparing weapon accuracy, it is important to also consider the scopes.
Borderlands ambiguously speaks of both Weapon Accuracy and Character Accuracy as simply "Accuracy".