Fallout: New Vegas weapon mods

Overview
One of the features added to Fallout: New Vegas is the ability to custom modify certain base weapons. While in Fallout 3 this was limited to the creation of custom weapons, Fallout: New Vegas takes this a step further by allowing the creation of weapon variants based on basic weapons by adding weapon mods.

Unique weapons cannot be equipped with weapon mods, with the exception of the Weathered 10mm Pistol, the Mercenary's grenade rifle and the holorifle. While unique guns usually have better base stats, Obsidian Entertainment introduced this inherent drawback of unique weapons to balance out unique and normal weapons and make the choice less of an obvious decision and more of a preference. However, some unique variants have both mods and better base stats. Such is the case of the Varmint Rifle's unique variant, the Ratslayer, which has all of the mods the Varmint Rifle can be equipped with.

By themselves, the weapon mods are weightless and serve no function but, once attached to their specified weapon, will change the characteristics, look and/or function to create a distinct variant. The weapon mods range from scopes and silencers to extended mags and several in-between. In the case of the Varmint Rifle and other such weapons there exists more than one different type of modification. While the player is not limited in the amount of total mods they can apply to a single weapon, they are limited to one of each type of mod per single weapon and therefore are not able to stack attributes like increased rate of fire.

Once a weapon mod is attached to a weapon it cannot be removed and remains a permanent feature of that weapon, along with its added attribute. However, this might not always be a good thing. For example, extended magazines are almost always beneficial, unless the magazine must be reloaded on a shell by shell basis (ex: Cowboy Repeater), forcing a longer reload (not necessarily forcing the reload to be longer, since pressing the fire button stops the reload); scopes also have pros and cons, as they may increase maximum range, but make the gun harder to use in close combat situations.

The addition of a mod to a weapon will permanently increase the overall monetary value of that weapon by the value of the mod, even if the weapon is completely broken at the time it is applied.

Usage
Weapon mods are attached via the Pip-Boy. To attach a weapon mod one must have both the weapon it is intended for and the mod in their inventory. Highlight the weapon within the "weapons" section of the Pip-Boy, then select the modding menu via the button as indicated in the top right of the info panel. After selecting a mod, the weapon name will have a + after it to show it has been improved, e.g. Varmint Rifle+. Once a weapon mod has been installed it cannot be removed. Weapon mods that have not yet been attached to a weapon will appear in the "misc" items section of the Pip-Boy.

Pistols

 * ¹ The mod can also be attached to either the laser RCW or recharger pistol with full effects.

Rifles

 * ¹ The description incorrectly states that condition is increased by 50%.


 * ² The mod can also be attached to either the laser RCW or recharger pistol with full effects.

Vendors
There are currently 10 vendors who offer weapon mods in the Mojave Wasteland, with additional vendors included within add-on areas. Inventory of mods changes with stock rotation every 72 hours game time.

1 After completion of Honest Hearts

Tiers

 * Guns Tier 1
 * Varmint Rifle
 * .357 Magnum revolver
 * 9mm pistol


 * Guns Tier 2
 * 10mm pistol
 * 9mm submachine gun
 * Cowboy Repeater
 * Service Rifle


 * Guns Tier 3
 * .44 Magnum revolver
 * Silenced .22 SMG
 * 10mm submachine gun
 * Hunting rifle


 * Guns Tier 4


 * Guns Tier 5


 * Energy Tier 1
 * Laser rifle
 * Plasma rifle


 * Energy Tier 2
 * Laser RCW
 * Flamer
 * Recharger pistol


 * Energy Tier 3
 * Gatling laser
 * Plasma caster


 * Explosives Tier 1
 * Grenade rifle


 * Explosives Tier 2
 * Missile launcher


 * Explosives Tier 3
 * Fat Man
 * Grenade machinegun


 * NCR Tier 1


 * Dead Money Tier 1


 * Honest Hearts Tier 1


 * Old World Blues Tier 1
 * K9000 Mod - Mentat Chow
 * K9000 Mod - Resla Roil
 * LAER Mod - Auxiliary Recharger Clip
 * LAER Mod - Prismatic Lens

Achievements/Trophies
Attaching 20 mods to weapons grants the Mod Machine achievement/trophy.

Behind the scenes
According to J.E. Sawyer, Fallout: New Vegas' project director and lead designer, during brainstorming and development, an appropriate skill level and a workbench would be required to attach a weapon mod. This was later scrapped during development because it came down to the player having already spent a sum of caps for the mod that they wanted to use as soon as they bought it, making the price and usefulness of the mod the main driving force toward the purchase, rather than skills and accessibility to workbenches.