All MW3 Aftermarket Parts & how to unlock them

Each MW3 and Warzone season brings new Aftermarket Parts that can tweak how the best guns work.

Season 5 introduces six new attachments, reintroducing unique AW weapons such as the Blunderbuss Shotgun with a Barrel conversion kit, and bringing the total number to over 30.

Here’s how to unlock every Conversion Kit, all the compatible weapons, and what they do.

How to get MW3 & Warzone Conversion Kits

Most Aftermarket Parts, also called Conversion Kits, can be unlocked via Armory Unlocks, in which players have to complete a specific number of multiplayer, Warzone, or Zombies challenges.

Some are available through the Battle Pass or the Weekly Challenges system, in which players need to complete five multiplayer, Warzone, or Zombies challenges for a specific seasonal week.

Every Aftermarket Part in MW3 & Warzone

Season 5

Aftermarket Part	Compatibility	Description
JAK Widemouth Barrel	MORS	Resembling CoD AW and WWII’s Blunderbuss, provides the MORS Sniper Rifle a widemouth barrel designed to hold “magnetic ball projectiles” that expand upon firing.
JAK Slash	Weapons with underbarrel capabilities	Vertical grip that functions as a combat knife, replacing your melee attack with a “lethal slash.”
JAK Protean	RAAL	Gives the RAAL a “telescoping barrel” with full-auto and semi-auto fire options.
JAK Cataclysm	RPK	Equips the RPK LMG with.50 Cal ammunition while retaining its high-capacity drum mag.
JAK Devastators	Reclaimer 18	Allows you to wield two Reclaimer 18 Shotguns at the same time.
JAK Deathmarch	BAL-27	Replaces the standard ammunition with high-voltage power cells and equips a photonic scatter barrel.

The Season 5 update will expand further the Aftermarket Parts roster by introducing six new attachments.

Season 4

In-game look	Aftermarket Part	Unlock method	Compatibility	Description
	JAK Gunslinger	Complete five challenges from Season 4 Week 7	Basilisk	Allows the Basilisk revolver to carry eight rounds of .357 ammunition, increases its rate of fire, and grants “near-instantaneous” trigger action
	JAK Volkh	Complete five challenges from Season 4 Week 6	KV Inhibitor	Stock and receiver mod that grants two-round burst with minimal dispersion
	JAK Decimator	Get 30 Suppressed SMG Kills	Lachmann Shroud	Lets the Lachmann Shroud fire in full auto mode
	JAK Intimidator	Get 15 headshots with Sidearms (Pistols)	Renetti	Turns the Renetti into a single-shot weapon
	JAK Thumper-556	Complete five challenges from Season 4 Week 4	RGL-80 + other Launchers	Shoots projectiles at higher velocities and distances
	JAK Scimitar Kit	Complete five challenges from Season 4 Week 3	FJX Horus	Unlocks a “high-capacity drum mag” as well as improved range and recoil control
	JAK Requiem	Complete five challenges from Season 4 Week 2	Kastov 762 + Kastov 545	Grants a system designed to “eliminate vertical recoil”
	JAK Harbinger Kit	Complete five challenges from Season 4 Week 1	M4	Turns the M4 into a deadly Rifle chambered in .50 Cal ammo with a slow fire rate, bullet velocity, and “significant increase in recoil.”

Season 3

In-game look	Aftermarket Part	Unlock method	Compatibility	Description
	JAK Shadow Titan Kit	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	Bruen Mk9	Converts the Bruen Mk9 into a compact, suppressed light support weapon
	JAK Jawbreaker	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	KV Broadside	Converts the KV Broadside Shotgun into an automatic Battle Rifle
	JAK Cutthroat	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	MCW, MTZ, M4, and AMR9	3D-printed stock that provides speed and stability while ADS
	JAK Revenger Kit	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	BP50	Conversion Kit that gives the BP50 a shortened receiver and high-capacity magazine
	JAK Wardens	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	Lockwood Mk2	Turns the Lockwood Mk2 into the iconic Model 1887 Akimbo Shotguns
	JAK Atlas Kit	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	AMR9	Converts the AMR9 into a 5-round burst weapon chambered in 556
	Photonic Charge Barrel	Get the MORS, reach max level and get 100 one-shot Kills	MORS	A hyper-advanced barrel that changes the fire nature of the trigger hold and release to let off a high-powered shot
	JAK Patriot	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	M16	Turns the M16 into a fully automatic rifle featuring a heavy ported barrel built to provide better recoil control and aim stability

Season 2

In-game look	Aftermarket Part	Unlock method	Compatibility	Description
	JAK Burnout	Reach Level 25, activate the Armory Unlock, and complete three Daily Challenges	Holger 26	Enables a specific firing mode with a significantly higher fire rate, and risk of overheating leading to increased spread
	JAK Tyrant 762 Kit	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	Longbow	Replaces the receiver and magazine to support 7.62 BLK ammunition, transforming the gun into a “harder-hitting weapon”
	JAK Limb Ripper	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	Several weapons	Enhances the maneuverability involving the complete removal of the stock
	JAK Maglift Kit	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	Haymaker	Strengthens the magwell, bolt, and trigger assembly to support the use of an oversized drum magazine
	JAK Glassless Optic	Reach Level 25, activate the Armory Unlock, and complete three Daily Challenges	Several weapons	A compact reflex optic without glass which provides a sharp and unobstructed view
	JAK Backsaw Kit	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	Holger 556	Enhances the maneuverability involving the complete removal of the stock
	JAK Outlaw-277 Kit	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	BAS-B	Transforms the BAS-B into a lever-action rifle, reducing its firing speed but significantly improving accuracy

Season 1

In-game look	Aftermarket Part	Unlock method	Compatibility	Description
	JAK Purifier	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	MTZ-556, Holger 556, DG-56, SVA 545, RAM-7, MTZ-762, BAS-B, Sidewinder, Riveter	An underbarrel flamethrower
	JAK Headhunter Carbine Conversion	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	Rival-9	Turns the Rival-9 into an Assault Rifle with “three-round burst”
	JAK Bullseye	Reach Level 25, activate the Armory Unlock, and complete two Daily Challenges	Most weapons categories	Compact dot Optic that provides a clear and precise sight picture
	JAK Beholder Rifle Kit	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	TYR	A long and heavy barrel that increases range, recoil control, and damage range, transforming the gun into a single-shot Rifle
	JAK Signal Burst	Reach Level 25, activate the Armory Unlock, and complete three Daily Challenges	Rival-9	Grants the Holger 556 four-round bursts
	JAK Ettin Double Barrel Kit	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	AMR9	Creates a pair of stacked barrels that fire simultaneously, resulting in double the damage
	JAK BFB	Reach Level 25, activate the Armory Unlock, and complete eight Daily Challenges	Many Assault Rifles, Submachine Guns, Battle Rifles, Marksman Rifles, and Sniper Rifles	Minimizes recoil while notably amplifying muzzle sound
	JAK Thunder LMG Kit	Reach Level 25, activate the Armory Unlock, and complete five Daily Challenges	Sidewinder	Features a high-capacity magazine and progressively increases its firing rate

What do MW3 & Warzone Aftermarket Parts do?

Aftermarket Parts are attachments unlocked separately from Weapon Rank – usually through a challenge. These can be as simple as a new Muzzle or Optic, or a Conversion Kit that completely changes how a weapon behaves.

These attachments can improve weapon stats such as range, damage, and recoil control, transform a weapon’s category by converting an Assault Rifle into a powerful SMG or heavy LMG, and provide better sight or mobility with specific accessories like Optics or Stocks.

Why are Aftermarket Parts important?

Aftermarket Parts have become an important feature due to their impact on MW3 and Warzone’s meta weapons. Some can even turn underrated weapons into meta contenders or popular picks, requiring several nerfs to balance them.

If you’re interested in unlocking more content through grinding, check out how to unlock the Molten Obsidian camo and every event available offering a ton of free rewards.