Fallout 3 weapons

Legend

 * DMG / HIT or SHOT: This information comes straight from the G.E.C.K. and shows the damage caused by a single click of the mouse/trigger. For most small guns, that's a single bullet, but for shotguns it's a single shell (containing several small pellets), and for the Gatling laser it's a single beam. This stat is most useful for comparing semi-automatic weapons like rifles, where you can see the full damage caused by a single shot, regardless of how long it takes to load and fire the next one.
 * DPS: This stands for damage per second.
 * MDPS: This is the modified damage per second number that takes critical hits into account. It assumes a non-V.A.T.S. attack, a Luck of 5, no perks (Finesse, Survival Expert, etc.), 100 skill and 100 weapon condition.
 * ROF: This stands for rate of fire in shots per second.
 * SPRD: This is the Min Spread stat from the G.E.C.K. (the Spread stat is not used). It refers to the accuracy of a ranged weapon. 0 means the weapon can potentially fire perfectly straight, if stance, weapon skill, and weapon condition are optimal. Anything above 0 means the shots may deviate from center by that many degrees regardless of stance, skill, or condition.
 * CRIT % MULT: The multiplier applied to your character's critical hit chance. This modifier applies to each individual attack you make (e.g. each 5mm bullet fired from your minigun). For example, if your character has a critical hit chance of 5%, and the weapon you're using has a CRIT % MULT of x2, then each shot has a 5% x 2 =10% chance to critically hit. For automatic weapons (assault rifles, SMGs, miniguns, etc.) the Crit % Mult stat in the G.E.C.K. is divided by the G.E.C.K.'s Fire Rate stat, hence the very small multiplier for automatic weapons. This is done to compensate for the sheer number of bullets being fired. Note that single V.A.T.S. attack, with automatic weapons, only checks for critical hit once, applying damage bonus for all bullets in such attack if critical hit is done.
 * CRIT DMG: The amount of damage that is added when you score a critical strike. The more specialized Sneak Attack Critical deals twice the damage of a common critical strike.
 * AP: The amount of Action Points used per shot in V.A.T.S.
 * AOE: This stands for area of effect it's an unknown unit of measurement displayed in the G.E.C.K.
 * HP: This is the Health stat from the G.E.C.K. It determines how fast a weapon breaks down. The more HP, the slower the rate of decay.
 * MAG: The magazine capacity of the firearm. Basically, how much ammunition it can hold.
 * V:W: Value to Weight ratio.

Unique: - A designation for any of the "named" versions of common weapons, the unique moniker is used within these charts to define which common weapons can be used as spare parts for repairs - unique weapons are listed in green.

Pistols

 * Unique weapons are highlighted with a darker background
 * Pistols are affected by Gunslinger.

Rifles

 * Unique weapons are highlighted with a darker background
 * Rifles are affected by Commando.
 * All assault rifles fire in 3-round bursts in V.A.T.S., except the Perforator which fires in 2-round bursts.

Shotguns

 * Unique weapons are highlighted with a darker background
 * Sawed-off shotguns are affected by Gunslinger.
 * All other shotguns are affected by Commando.

SMGs

 * Unique weapons are highlighted with a darker background
 * SMGs are affected by Gunslinger.
 * SMGs fire in 4-round bursts in V.A.T.S..

Direct-Fire

 * Unique weapons are highlighted with a darker background
 * Damage calculated with the inclusion of Pyromaniac perk adjustments.
 * ¹ Damage is unaffected by Pyromaniac
 * Miniguns and Gatling lasers fire in 8-round bursts in V.A.T.S.
 * Flamers fire in 3-round bursts in V.A.T.S.
 * Heavy incinerator fires 4 projectiles in V.A.T.S., while only spending single point of ammunition

Area-of-Effect

 * Unique weapons are highlighted with a darker background
 * Area-of-Effect weapons have a Crit % Modifier of 0, which eliminates any chance to critically hit with them.

Energy Pistols

 * Unique weapons are highlighted with a darker background
 * Pistols are affected by Gunslinger
 * Colonel Autumn's laser pistol fires in 2-round bursts in V.A.T.S..

Energy Rifles

 * Unique weapons are highlighted with a darker background
 * Rifles are affected by Commando
 * Destabilizer, although automatic, fires only one projectile in V.A.T.S.

Placed

 * Damage calculated under Demolition Expert (3 Ranks)

Thrown

 * † Damage is unaffected by Demolition Expert
 * Damage calculated under Demolition Expert (3 Ranks)

Bladed

 * Unique weapons are highlighted with a darker background
 * Damage calculated under Pyromaniac (1 Rank)

Blunt

 * Unique weapons are highlighted with a darker background

Unarmed

 * Unique weapons are highlighted with a darker background

Custom-built weapons

 * Red codes are for the Schematics.
 * Cryolator, also a custom-built weapon, was cut from the game

Cut Content
Cut content, these weapons are only available through console commands.

Cut content weapons that are only obtained through glitches OR console commands.

Concept Art Weapons
These weapons were made into concept art but never made into the base Fallout 3:
 * Cryolator
 * Mason jar mine
 * Piggy bank grenade
 * Air hammer gun