The Muzzle Brake appears only in one mission, "Ghost Stories". It is attached to most of the MTAR-X2s used by the Federation in the space orbit. This muzzle brake has a different appearance from the one seen in multiplayer and Extinction.
The Muzzle Brake appears in multiplayer and costs 4 Squad Points. It gives every weapon 20% more range, except for Marksman Rifles and Shotguns, which get 15% more range. It works great on shotguns due to their very low range, despite the lower range amount compared to other weapon types. Using this in conjunction with Slug Rounds on a shotgun will allow the player to kill enemies at a range more comparable to a submachine gun's effective range.
It also works good on submachine guns, because although they do not have as low of range as shotguns, they do have low range. Using this on a submachine gun in conjuction with a Foregrip allows them to be even more effective in medium range.
The Muzzle Brake can be found as a searchable item in Extinction maps Point of Contact, Nightfall, Mayday and Awakening. The Muzzle Brake can be added to any weapon excluding pistols, sniper rifles, and guns with an integrated silencer (i.e. Honey Badger). However, upgrading the player's pistol will give it a Muzzle Brake.
In "Awakening", the muzzle brake can now be equipped on the VKS and the K7, despite these weapons having integrated silencers.
The Muzzle Brake conflicts with the ARK attachment, as the ARK is also an attachment which fixates at the end of the barrel of a weapon. The ARK is usually better than the Muzzle Brake overall, so users should not hesitate to swap out the Muzzle Brake for an ARK if given the opportunity. However, certain weapons will have their view of the iron sights obstructed by the ARK on account of how large the ARK is, whereas the Muzzle Brake never blocks the sight picture. Still, the ARK is a better choice for said weapons.
The Pistol ARK Upgrade will modify the Muzzle Brake attachment upgrade for the pistols to give the pistol an ARK instead. When the Pistol ARK Upgrade is active, the pistol will have no way to equip a Muzzle Brake.