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Call of Duty: Modern Warfare 3has added its third set of challenges this season, adding a new aftermarket part for players to unlock. This week, completing five challenges will unlock the JAK Cutthroat stock, the first aftermarket stock in MW3.
Installing this attachment will greatly increase your strafe speed and overall mobility, making this a great pick for aggressive builds. If you want to strafe as fast as possible, read on to learn how this attachment works and how to complete this week’s challenges as quickly as possible. Remember: you only need to complete a total of five challenges from this week. They can be from Multiplayer, MWZ, Warzone, or a mix of the three.

Week 3 Challenge Reward
After you complete five of this week’s challenges, you’ll unlock theJAK Cutthroat stockfor most assault rifle and SMG platforms. This stock significantly increases your strafe speed and general mobility while equipped, although it comes at the cost of recoil control and aiming idle sway.
For most weapons, you can expect a27% strafe speed upgrade.Most attachments give an 8-15% bonus, for comparison. While powerful, this weapon may only be installed on the following weapon platforms:

The in-game description states that this attachment works on the MCW platform. This is false. You cannot install this attachment on any MCW weapon.
2,500 XP

5,000 XP
Get 5 kills with a gun-butt of a recommended weapon.
Get 15 kills against operators who are blinded or stunned with recommended SMGs.
Place at the top of the scoreboard 3 times.
7,500 XP
Get 2 kills in a row without taking damage with a recommended SMG 5 times.
Use your Lethal to kill 5 enemies affected by a Shock Stick.
10,000 XP
Get 10 Mangler kills with a recommended weapon.
Get 100 kills in a single deployment 5 times with a recommended weapon.
In Warzone, open 75 loot caches.
In Warzone Rebirth Island, get 15 kills in the northwest region (Dock, Control Center).
In Warzone Rebirth Island, get 15 kills in the southeast region (Stronghold, Living Quarters).
In Warzone, revive a teammate 15 times.
In Warzone Rebirth Island, get 15 kills in the northeast region (Bioweapons Industries, Harbor, Chemical Eng.).
In Warzone Rebirth Island, get 15 kills in the center region (Prison Headquarters, Factory).