So... I'm Antistar, the author of http://www.fallout3nexus.com/downloads/file.php?id=3388 (WMK) for Fallout 3. Obsidian took inspiration from WMK in their implementation of the weapon modding system in Fallout New Vegas; something which I am quite proud of and flattered by. I like Obsidian's take on it; fairly similar to mine, but still with some key differences. There are aspects of my approach that I think work well, and aspects of their approach that I think work well too.
But I like it. So much so that I wanted to add to it... expand upon it, you might say.
I'm putting this WIP thread up sooner than I would have preferred, largely because I've seen lots of weapon modding overhauls popping up on FNVNexus (none of them are quite what I want or what I've been planning though), and I thought I should let people know what I'm working on. So yes, before anyone mentions it, I am aware of the other similar mods around. I believe what I'm doing is... worthwhile, though; I'll leave it at that.
This is going to take a while to get to a state ready for release (I don't want to do multiple incremental versions with only a few weapons implemented each time), but I'll keep you all posted on my progress.

In the meantime, check out the screenshots below; they should hopefully give some idea of the direction I'm taking this. Comments and suggestions are welcome.
Summary
- All weapons get the maximum of three applicable weapon mods; this includes unique weapons.
- Some existing weapon mods are newly applied to weapons besides their defaults...
- But many more are newly created weapon mods.
- Some weapon mods can be applied to multiple different weapons.
- Unique weapons without a common counterpart (for example That Gun and This Machine) receive one.
- New and altered art assets to visually depict a large proportion of the new weapon mods.
- Chance to find weapon mods in loot.
- More weapon mods available from merchants (to compensate for more types being available).
Planned/potential features beyond Version 1.0
- Weapon mods for melee weapons (planned).
- The ability to remove weapon mods (if possible).
Screenshots
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/9mm_pistol01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/maria01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/maria02.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/maria03.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/127mm_pistol01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/silenced_22_pistol01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/223_pistol01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/lucky01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/44magnumrevolver02.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/mysterious_magnum01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/hunting_revolver01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/hunting_revolver02.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/ranger_sequoia01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/ranger_sequoia02.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/9mm_smg01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/9mm_smg_unique01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/127mm_smg01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/silenced_22_smg01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/caravan_shotgun01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/caravan_shotgun02.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/hunting_shotgun01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/hunting_shotgun_unique01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/lever_shotgun01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/riot_shotgun01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/sawed_off_shotgun01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/sawed_off_shotgun_unique01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/single_shotgun01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/m1garand01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/m1garand02.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/alien_blaster01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/laser_pistol01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/pew_pew01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/pew_pew02.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/plasma_defender01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/plasma_pistol01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/pulse_gun01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/pulse_gun02.jpg (Ahem. I'm charging my laser.)
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/recharger_pistol01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/gauss_rifle01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/gauss_rifle_unique01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/laser_rcw01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/laser_rifle_unique01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/multiplas01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/plasma_rifle01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/plasma_rifle_unique01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/plasma_rifle_dualcell02.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/recharger_rifle01.jpg
- http://i21.photobucket.com/albums/b300/jlollback/falloutnv/tri_beam01.jpg
Weapon Mod List
(May be subject to change)
Changed Weapon Mods
9mm Pistol Scope -> Small Handgun Scope
10mm Pistol Laser Sight -> Laser Sight
Grenade Rifle Long Barrel -> 40mm Launcher Long Barrel
Hunting Shotgun Choke -> 12 Gauge Shotgun Choke
Laser RCW Recycler -> Laser Recycler
Laser Rifle Beam Splitter -> AEP/AER Laser Beam Splitter
Laser Rifle Focus Optics -> AEP/AER Laser Focus Optics
Laser Rifle Scope -> AEP/AER Laser Scope
Plasma Rifle Mag. Accelerator -> Plasma Weapon Mag. Accelerator
Key
* = Vanilla weapon mod
+ = New weapon mod (or existing one newly applied)
# = Icon needed (largely for my own reference)
Handguns
.223 Pistol / That Gun
+ Laser Sight - Decreases spread, adds laser sight effect.
+ .223 Pistol Long Barrel - Increases damage (+3). #
+ Small Handgun Scope - Adds short-range scope.
.357 Magnum Revolver / Lucky
* .357 Revolver Long Barrel - Increases damage (+3).
* .357 Revolver HD Cylinder - Increases condition (+50%).
+ .357 Revolver Custom Action - Increases rate of fire. #
.44 magnum revolver / Mysterious Magnum
* .44 Revolver Heavy Frame - Increases condition (+50%).
* .44 Revolver Scope - Adds a close to mid range scope.
+ .44 Revolver Long Barrel - Increases damage (+3). #
9mm Pistol / Maria
* 9mm Pistol Extended Mags - Increases ammunition capacity (+7).
* Small Handgun Scope - Adds short-range scope.
+ 9mm Silencer - Silences the weapon.
10mm Pistol
* 10mm Pistol Extended Mags - Increases ammunition capacity (+4).
* Laser Sight - Decreases spread, adds laser sight effect.
* 10mm Pistol Silencer - Silences weapon.
12.7mm Pistol
* 12.7mm Pistol Silencer - Silences the weapon.
+ 12.7mm Pistol Extended Mags - Increases ammunition capacity (+3).
+ Laser Sight - Decreases spread, adds laser sight effect.
Hunting Revolver / Ranger Sequoia
+ Hunting Revolver HD Cylinder - Increases condition (+50%).
+ Hunting Revolver Long Barrel - Increases damage (+5). #
+ Hunting Revolver Scope - Adds a close to mid range scope.
Silenced .22 Pistol
+ Sil. .22 Pistol Ext. Mags - Increases ammunition capacity (+8).
+ Laser Sight - Decreases spread, adds laser sight effect.
+ Sil. .22 Pistol Long Barrel - Increases damage (+2). #
SMGs
9mm SMG / Vance's 9mm SMG
* 9mm SMG Drums - Increases ammunition capacity (+30).
* 9mm SMG Light Bolt - Increases rate of fire.
+ 9mm Silencer - Silences the weapon.
10mm SMG
* 10mm SMG Extended Mags - Increases ammunition capacity (+10).
* 10mm SMG Recoil Comp. - Decreases spread.
+ 10mm SMG Light Bolt - Increases rate of fire.
12.7mm SMG
* 12.7mm SMG Silencer - Silences the weapon.
+ Laser Sight - Decreases spread, adds laser sight effect.
+ 12.7mm SMG Light Bolt - Increases rate of fire.
Silenced .22 SMG
* Sil. .22 SMG Exp. Drums - Increases ammunition capacity (+60).
+ Laser Sight - Decreases spread, adds laser sight effect.
+ Sil. .22 SMG Long Barrel - Increases damage (+2). #
Shotguns
Caravan Shotgun
+ 20 Gauge Shotgun Choke - Decreases spread.
+ Caravan Shotgun Improved Parts - Increases condition (+50%). #
+ 20 Gauge Sawn-off Stock - Decreases weight (C.S. -1, S.S. -3). #
Hunting shotgun / Dinner Bell
* 12 Gauge Shotgun Choke - Decreases spread.
* Hunting Shotgun Long Tube - Increases ammunition capacity (+3).
+ Hunting Shotgun Composite Stock - Decreases weight (-3.5).
Lever-action Shotgun
+ 20 Gauge Shotgun Choke - Decreases spread.
+ Lever-action Shotgun Improved Parts - Increases condition (+50%). #
+ Lever-action Shotgun Long Tube - Increases ammunition capacity (+2).
Riot Shotgun
+ 12 Gauge Shotgun Choke - Decreases spread.
+ Riot Shotgun Improved Parts - Increases condition (+50%). #
+ Riot Shotgun Improved Seals - Increases damage (+5). #
Sawed-off Shotgun / Big Boomer
+ 12 Gauge Shotgun Choke - Decreases spread.
+ Sawed-off Shotgun Improved Parts - Increases condition (+50%). #
+ Sawed-off Shotgun Maple Stock - Decreases weight (-1). #
Single Shotgun
+ 20 Gauge Shotgun Choke - Decreases spread.
+ Single Shotgun Improved Parts - Increases condition (+50%). #
+ 20 Gauge Sawn-off Stock - Decreases weight (C.S. -1, S.S. -3). #
Rifles
Anti-materiel Rifle
+ Anti-mat. Rifle Custom Action - Increases rate of fire.
+ Anti-mat. Rifle Composite Stock - Decreases weight (-5). #
+ Anti-mat. Rifle Improved Muzzle Break - Increases damage (+10). #
Assault Carbine
* Assault Carbine Extended Magazines - Increases ammunition capacity (+6).
+ Assault Carbine Light Bolt - Increases rate of fire.
+ Carbine Silencer - Silences the weapon.
Battle Rifle / This Machine
+ Battle Rifle Composite Stock - Decreases weight (-5). #
+ Battle Rifle Long Barrel - Decreases spread. #
+ Battle Rifle Scope - Adds long-range scope.
BB Gun / Abilene Kid LE BB Gun
+ BB Gun Custom Mechanism - Increases rate of fire. #
+ BB Gun Improved Parts - Increases condition (+50%). #
+ BB Gun Increased Pressure - Increases damage (+1). #
Brush Gun
* Brush Gun Forged Receiver - Increases condition (+50%).
+ Brush Gun Long Tube - Increases ammunition capacity (+2).
+ Brush Gun Scope - Adds mid-range scope.
Cowboy Repeater / La Longue Carabine (may need to consider LLC separately)
* Cby. Rep. Custom Action - Increases rate of fire.
* Cby. Rep. Long Tube - Increases ammunition capacity (+4).
* Cby. Rep. Maple Stock - Decreases weight.
Hunting Rifle
* Hunting Rifle Custom Action - Increases rate of fire.
* Hunting Rifle Extended Mag - Increases ammunition capacity (+5).
* Hunting Rifle Scope - Adds long-range scope.
Light Machine Gun
* Light MG Expanded Drums - Increases ammunition capacity (+110).
+ Light MG Improved Rifling - Increases damage (+2). #
+ Laser Sight - Decreases spread, adds laser sight effect.
Marksman Carbine / All-American
+ 5.56mm Carbine Extended Mags - Increases ammunition capacity (+6).
+ Marksman Carbine Improved Rifling - Increases damage (+2). #
+ Carbine Silencer - Silences the weapon.
Service Rifle
* Svc. Rifle Forged Receiver - Increases condition (+50%).
* Svc. Rifle Upgraded Springs - Increases rate of fire.
+ 5.56mm Carbine Extended Mags - Increases ammunition capacity (+6).
Sniper Rifle / Gobi Campaign Scout Rifle
* Sniper Rifle Carbon Fiber Parts - Decreases weight (-5).
* Sniper Rifle Suppressor - Reduces weapon noise.
+ Sniper Rifle Extended Mags - Increases ammunition capacity (+5).
Trail Carbine
* Trail Carbine Scope - Adds mid-range scope.
+ Trail Carbine Composite Stock - Decreases weight (-2.5).
+ Trail Carbine Forged Receiver - Increases condition (+50%).
Varmint Rifle / Ratslayer
* Varmint Rifle Extended Mags - Increases ammunition capacity (+3).
* Varmint Rifle Night Scope - Adds long-range night scope.
* Varmint Rifle Silencer - Silences the weapon.
Energy Weapons - Pistols
Alien Blaster
+ Alien Blaster Experimental Mag. Accel. - Increases speed of alien projectile.
+ Extended Alien Power Cells - Increases ammunition capacity (+5).
+ AEP/AER Laser Scope - Adds scope.
Plasma Defender
+ Plasma Defender External Heatsink - Increases condition (+50%). #
+ Plasma Defender Inline Mag. Accel. - Increases speed of plasma projectile. #
+ Plasma Defender Scope - Adds short-range scope. #
Plasma Pistol
+ Plasma Pistol Added Injector Cylinders - Increases rate of fire. #
+ Plasma Pistol Thickened Chamber Casing - Increases condition (+50%). #
+ Plasma Weapon Mag. Accelerator - Increases speed of plasma projectile. #
Laser Pistol / Pew Pew
+ AEP/AER Laser Beam Splitter - Creates two beams that together do increased damage (+30%). (Will almost certainly be changed, since this effect doesn't work.)
+ AEP/AER Laser Focus Optics - Increases damage (+3).
+ AEP/AER Laser Scope - Adds scope.
Pulse Gun
+ Pulse Gun Extra Battery Socket - Doubles ammunition capacity. #
+ Pulse Gun Extra Bulbs - Increases condition (+50%). #
+ Pulse Gun Recycler Core - Replenishes ammunition (1/4 shots).
Recharger Pistol
* Laser Recycler - Replenishes ammunition (1/4 shots).
+ Recharger Experimental Core - Increases ammunition capacity (+5).
+ Recharger Supercharger Coil - Increases damage (+3). #
Energy Weapons - Rifles
Gauss Rifle / YCS/186
+ Gauss Rifle Composite Stock - Decreases weight (-2). #
+ Gauss Rifle Exp. Cell Assembly - Doubles ammunition capacity. #
+ Gauss Rifle Improved Mag. Shielding - Increases condition (+50%). #
Laser RCW
* Laser Recycler - Replenishes ammunition (1/4 shots).
+ Laser RCW Composite Stock - Decreases weight (-1). #
+ Laser RCW Scope - Adds medium-range scope. #
Laser Rifle / AER14 Prototype
* AEP/AER Laser Beam Splitter - Creates two beams that together do increased damage (+30%). (Will almost certainly be changed, since this effect doesn't work.)
* AEP/AER Laser Focus Optics - Increases damage (+3).
* AEP/AER Laser Scope - Adds scope.
Plasma Rifle / Q-35 Matter Modulator
* Plasma Weapon Mag. Accelerator - Increases speed of plasma projectile.
+ Plasma Rifle Dual-Cell Harness - Doubles ammunition capacity. #
+ Plasma Rifle Synchronised Aperture Stabilisers - Increases rate of fire. #
Recharger Rifle
+ Laser Recycler - Replenishes ammunition (1/4 shots).
+ Recharger Experimental Core - Increases ammunition capacity (+5).
+ Recharger Supercharger Coil - Increases damage (+3). #
Multiplas Rifle
+ Plasma Rifle Dual-Cell Harness - Doubles ammunition capacity. #
+ Multiplas Upg. Discharge Init. Capacitors - Increases rate of fire. #
+ Multiplas Magnetic Stabiliser - Decreases Spread.
Tri-beam Laser Rifle
+ Tri-beam Laser Rifle Dual-Cell Harness - Doubles ammunition capacity. #
+ Tri-beam Laser Rifle Polished Emitter - Decreases Spread. #
+ Tri-beam Laser Rifle Sawn-off Stock - Decreases weight (-3). #
Heavy Weapons
Flamer
* Flamer Expanded Tanks - Increases ammunition capacity (+60).
+ High Pressure Fuel System - Increases rate of fire. #
+ Reinforced Fuel Hoses - Increases condition (+25%). #
Gatling Laser
* Gat. Laser CF Frame: Decreases weight (50%).
* Gat. Laser Focus Optics - Increases damage (+3).
+ Embedded Laser Sight - Decreases spread, adds laser sight effect. #
Incinerator / Heavy Incinerator
+ Incinerator Extra Tanks - Doubles ammunition capacity.
+ Incinerator Stripped Down - Decreases weight (-4). #
+ Reinforced Fuel Hoses - Increases condition (+25%). #
Minigun / CZ57 Avenger
* Minigun Damped Subframe - Reduces spread.
* Minigun High-Speed Motor - Increases rate of fire.
+ Minigun Chromed Barrels - Increases condition (+25%). #
Plasma Caster
* Plasma Caster HS Electrode - Increases rate of fire.
+ Plasma Caster Improved Parts - Increases condition (+50%). #
+ Laser Sight - Decreases spread, adds laser sight effect.
Tesla Cannon / Tesla-Beaton Prototype
+ Tesla Cannon Improved Shielding - Increases condition (+50%). #
+ Tesla Cannon Internal Battery - Doubles ammunition capacity.
+ Tesla Cannon Scope - Adds medium-range scope.
Explosive Weapons
Fat Man
* Fat Man Little Boy Kit - Decreases weight (50%).
+ Fat Man Upgraded Hydraulics - Increases range (+50%). #
+ Fat Man Improved Parts - Increases condition (+50%). #
Grenade Launcher
+ 40mm Launcher Chromed Barrel - Increases condition (+50%). #
+ 40mm Launcher Long Barrel - Increases range (+100%).
+ Grenade Launcher Composite Stock - Decreases weight (-4). #
Grenade Rifle / Thump-Thump
* 40mm Launcher Long Barrel - Increases range (+100%).
+ 40mm Launcher Chromed Barrel - Increases condition (+50%). #
+ Grenade Rifle Composite Stock - Decreases weight (-2). #
Grenade Machinegun / Mercy
* Grenade MG High-Speed Kit - Increases rate of fire.
+ Grenade MG Internal Stabiliser - Reduces spread. #
+ Grenade MG Tempered Barrel - Increases condition (+50%). #
Missile Launcher / Annabelle
* Miss. Launcher Guidance Sys. - Decreases spread.
+ Miss. Launcher Aux. Tube - Doubles ammunition capacity. #
+ Miss. Launcher Composite Frame - Decreases weight (-5). #