Recoil

Not to be confused with Accuracy.

Recoil is described as the physical kick of a weapon when firing, represented by the target reticule moving up a certain distance and/or shaking slightly. This can be countered by various recoil reduction mods, but remember that recoil is separate from a weapon's accuracy, which usually cannot be improved through modding.

However, it is relevant to note that while gun accuracy will not improve through modding, and bullets will spread the same as they normally would, on weapons with high recoil or kick such as the Supra, the decreased recoil can make it easier to land shots onto enemies.

Accuracy is a separate mechanic from physical recoil, but both can go hand-in-hand with some weapons. It is described as the set path bullets will take when fired. The lower the number, the less accurate the weapon is and the more the bullets will spread over distances. As mentioned above, accuracy usually cannot be improved through mods, a few mods can actually decrease accuracy. Recoil however, can be relieved with various mods. Fire rate also increases recoil in some weapons, such as the Grakata, which require burst firing in order to counter heavy recoil without modding.
 * Heavy Caliber grants additional damage to rifles, at the cost of making the weapon's accuracy suffer. Weapons with 100 base accuracy will produce a new base accuracy number, rather than subtracting the mod effect number from 100.
 * Magnum Force grants additional damage to pistols, at the cost of making the weapon's accuracy suffer. Weapons with 100 base accuracy will produce a new base accuracy number, rather than subtracting the mod effect number from 100.
 * Vicious Spread grants additional damage to shotguns, at the cost of making the weapon's pellet spread increase. Shotguns with a large pellet cone already should avoid this mod, as it will require even closer combat in order to take advantage of the extra damage.
 * ​Tainted Shell is the only mod that increases accuracy, reducing pellet spread at the cost of a reduced fire rate. Fire rate decrease can be countered by Shotgun Spazz.
 * Stabilizer reduces the recoil of rifles, with no negative side effect.
 * Vile Precision reduces the recoil of rifles, while also reducing the base firing rate. The fire rate decrease can be countered with Speed Trigger. Best used on the Grakata to increase accuracy and ammo efficiency.
 * Steady Hands reduces the recoil of pistols, with no negative side effect.

Weapons With High Recoil
These weapons are considered to have high recoil, and are prime candidates for recoil-reduction mods if available.
 * Brakk pistol
 * Bronco, Dual Broncos, Bronco Prime pistols
 * Snipetron, Snipetron Vandal sniper rifles
 * Vectis sniper rifle
 * Boar, Boar Prime shotguns
 * Hek shotgun
 * Gorgon machine gun
 * Supra machine gun
 * Kraken pistol
 * Lex and Aklex pistols
 * Seer pistol
 * Grakata rifle
 * Sicarus pistol
 * Cestra and Dual Cestra pistol

Trivia

 * Heavy Caliber and Magnum Force used to add recoil to weapons, instead of reducing accuracy, which made recoil-less weapons gain a pure damage boost. This change however made less sense then recoil as a higher damage bullet would create a larger kick and not necessarily have a negative effect on accuracy.