Accuracy (weapon)



In borderlands, Weapon Accuracy, also known as Accuracy Ratting, 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. This is an indicator of the angle at which the gun fires projectiles; As a note, this percentage determines the angle at which bullets come out of the gun, where 100 is 0° and any other percentages will fall between that and 11.25°

A rough equation for the maximum angle of deviation is angle = 7.48635 &minus; 0.07174 &times; accuracy , where angle is measured in degrees and accuracy is the percentage value.
 * Note: This is only a general equation; it is not an exact representation of the angle, and there are several outliers. For example, extremely inaccurate guns (0.0%–10%ish) do not fall on any linear or exponential equations within reason. Sledge's Shotgun has an accuracy of 0.0% and fires at an angle of 11.25°. Furthermore, guns with 35.0% are more accurate than guns with 37.7%.

You can convert the angle of spread to an "area" (solid angle) that bullets fire into using the equation
 * area = (129 000 /&pi;) &times; (1 &minus; cos&thinsp;angle),

where area is measured in square degrees.
 * A gun with 98% accuracy deviates up to 0.456°, firing into a target area of 1.299 deg2.
 * A gun with 90% accuracy deviates up to 1.030°, firing into a target area of 6.632 deg2.
 * A gun with 50% accuracy deviates up to 3.899°, firing into a target area of 95.06 deg2.
 * A gun with 50% accuracy deviates up to 3.899°, firing into a target area of 95.06 deg2.

The consequence of this is that gun accuracy should not be compared as a percentage, but as a distance from 100%.
 * A 98% accuracy (1.299 deg2) sniper rifle is twice as accurate as a 95.4% accuracy (2.581 deg2) sniper rifle.
 * A 91% accuracy machine gun (5.740 deg2) is 68.9% more accurate than an 87% accuracy machine gun (9.693 deg2).
 * A 26% accuracy shotgun (197.5 deg2) is 41.9% more accurate than an 11% accuracy shotgun (280.2 deg2).

Spread
Internally, Borderlands keeps track of a weapon's accuracy using a metric called "Spread". It is possible to convert back and forth from Weapon Card Accuracy and Spread with the formulas: Spread = 12 &minus; ( 0.12 &times; Accuracy ) Accuracy = ( 12 &minus; Spread ) / 0.12

Each weapon category has a "Base Spread", as described in the bellow table.

From there, this base spread can be modified by the parts that make up the weapon, according to the Borderlands stat modifiers formulas.

Scopes
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 a 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 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.

Others
Borderlands ambiguously speaks of both |Weapon Accuracy and Player Accuracy as simply "Accuracy".
 * Scattershot, Focus and Enforcer all improve Weapon Accuracy.
 * Proficiency improves Player Accuracy.