Unlike previous installments, weapons in Fallout 4 fall under three classifications: normal, legendary, and unique. Normal weapons have no special statistics on them whatsoever. Legendary weapons come with random bonuses applied to them, and are only dropped by legendary enemies. Unique weapons are weapons that are already named and will always retain the same special bonus. Uniques are typically either bought from merchants or are quest rewards. Normal and legendary weapons will change their name when mods are applied, unique weapons will not.
All stats are given with standard weapon modifications.
General Note: In the following descriptions, the statistics the are shown while playing the game will be referred to as in-game numbers, while the numbers used by the game's code will be referenced as internal numbers. Internal numbers can only be gathered through game editor or console use.
Accuracy (Accuracy): This is the Accuracy stat displayed in-game, which is derived from the internal game numbers for projectile deflection angles in an unknown way. See Spread for details on the internal measurements.
Action Point cost (Action point cost): The number of Action Points used per activation in V.A.T.S. Generally, this is a one shot equivalent for semi-automatic weapons, but automatic weapons may fire several rounds.
Ammunition used (Ammunition used): The type of ammunition the weapon uses. This may be changed by the use of receiver mods.
Armor piercing: The amount of the target's damage resistance the weapon ignores. Also known as armor penetration.
Bash damage: This is the amount of damage a projectile weapon does when used as a melee weapon.
Critical hit Damage (Critical hit Damage): Most unmodified weapons that achieve a critical hit adds twice the base amount of damage to the hit. The more specialized Sneak Attack Critical deals twice the damage of a common critical strike.
Damage (Damage per shot): This is the damage caused by a single click of the mouse/trigger. For most small guns, that's a single bullet, but for shotguns the damage is equally split between the shell's pellets, and for the Gatling laser it's a single beam.
Damage per second (Damage per second): The manually calculated maximum cyclic damage dealt in one second, expressed as rate of fire multiplied by damage. Weapons that require a reload every shot have damage per second shown including reload times; all others show sustained rates without reloads.
Magazine capacity or shots per reload (Magazine capacity (shots per reload)): The maximum ammunition capacity of the weapon or the maximum number of shots possible before requiring a reload.
Magnification: The scope or sight mod's magnification rating.
Range (Range): In-game, range is a generalized stat for how far a weapon's projectile can go before suffering from damage loss. How this number is derived from internal values and related to actual distances is unknown. There are two hidden internal range ratings, the minimum and maximum range. Between point blank and the minimum range, damage is full. Between minimum range and maximum range, damage decreases down to the out of range value at a linear rate. Beyond maximum range, damage is reduced by the out of range value. Typically, the out of range value is a 50% loss of damage, though some weapons are higher or lower. Distance for range is rated differently internally: most ranged weapons begin with range being 256 units and some research indicates that that 256 of these internal units is meant to equal approximately 12 feet, but more effort is needed to confirm.
Rate of fire (Rate of fire): The in-game given number gives the maximum cyclic number of shots/attacks per 10 seconds, without considering reloading. This is internally derived from the weapons attack delay rating divided by its speed rating However, if a weapon is converted to automatic or bolt-action fire, the time between shots becomes derived purely from its speed and/or firing animation duration.
Recoil: Recoil is the visible movement of the weapon upon firing. Like spread it is represented in maximum possible degrees from the center. Unlike spread which is the invisible possible deviation of the projectile from a perfect shot, recoil visibly moves the weapon and crosshairs, and can be additive with spread. Unlike spread which has a completely random direction, recoil has a limited "window" which the kick can move the weapon.
Reload / Reload speed: This is made up of at least two factors. The base reload speed is derived from the reload animation speed in seconds. There is also a second internal value called reload speed that affects reload time in an unknown way, beyond the fact that higher values result in faster reloads.
Sight time: This is the amount of time it takes to transition from hip firing to sighted or scoped state, in seconds.
Sighted spread: The amount a weapon's spread is reduced to when aiming down a sight or scope.
Spread (Accuracy): Spread is the hidden internal number of degrees from a perfectly centered shot that a projectile can potentially deflect. For example, a combat shotgun has a spread of 12°. When firing it, each of the 8 pellets produced by the weapon can proceed separately from between 0° to 12°, randomly generated, in a separately randomly generated 360° cone. Most weapons have a minimum spread, when the shooter is standing still and fully focused, and a maximum spread. The degree of spread somewhat corresponds to the width of the crosshairs. Spread increases with each shot, by an amount different for each weapon, and slowly reverts to base spread after a slight delay.
Stability: This is an internal value that represents the amount of movement a sight or scope has without player involvement. How the internal number relates to actual movement is currently unknown, beyond the fact that higher stability means less movement.
Value to weight ratio (Value to weight ratio): This is the manually calculated ratio of the base weapon value in caps to the weapon weight.
Weapon value in caps (Weapon value in caps): Base value of the weapon in caps. Resale value is affected by Barter skill.
Weight (Weapon weight): Weight value of the weapon that applies to encumbrance. Weapon weight also increases the amount of time it takes for you to ADS (aim down sights) or "scope." This is explained in a loading screen tool-tip
All these weapons count as non automatic weapons and thus work with either Gunslinger, Rifleman, or Sniper respectively, except the Cryolator, which is counted as a heavy gun and thus works with Heavy Gunner.
These weapons produce radiation damage, including both direct damage from explosions and damage over time from exposure and poisoning. There is some variance in how damage is dealt within this class of weapon; please consult each weapon's page for specific details. Also, the radiation page explains the unique ways that this kind of damage is handled by the game. These are affected by the perk Nuclear Physicist in terms of radiation damage.
In Fallout 4, the player character is able to rename any weapon, including unique weapons, at any weapons workbench. Renaming weapons does not affect any weapon stats. This primarily adds a level of personalizing to weapons and can help avoid accidentally disassembling a favored weapon.
Special and accented characters (i.e. alt-codes) can be used when renaming a weapon. Bold and italic can also be used.
Weapons may be modified in Fallout 4. Each weapon has modification 'slots' (e.g. barrel, grip, magazine, sights) that may be modified with increasingly powerful or useful mods by the player character based on their perks. However, the player character may salvage useful mods that are not yet available via the player character's perk level by simply modifying any weapon that already has the mod of interest. By replacing the mod of interest with any available mod the original mod goes into inventory and may then be used to alter the player character's chosen weapon without regard for their perk level. Unique weapons do not offer this capability; their special mods are 'reserved' and since they are unique, no other examples are available to be salvaged.
If a player character puts unique and legendary weapons in a container in a settlement, nearby NPCs, like settlers or even enemy attackers, can randomly take them and they may be irretrievable. Therefore, access to personal containers should be restricted, either by obstructing the expected path used by them to reach the container, or by the use of powered doors, holes, floating structures, etc.