In Brink for the PS3 and Xbox 360, the unlockable attachments in the game can be unlocked by playing through the four different challenges.
Each weapon may have a different set of attachments that can go with that particular weapon. Some weapons may accept a scope attachment, while others may just accept red dot sights or adjusted iron sights, etc.
Here is the list of unlockable attachments, and which challenges you need to complete to unlock them.
Be More Challenge
One Star Challenge – Duct Taped Magazines (increases reload speed of every second reload)
Two Star Challenge – Speed Holsters (switches to the weapon faster)
Two Star Challenge – Speed Slings (switches to the weapon faster)
Escort Duty Challenge
One Star Challenge – High Powered Scopes (enables zoom)
One Star Challenge – Muzzle Breaks (improves aim and changes flash pattern)
One Star Challenge – Red Dot Sights (replaces iron sight with red dot reticle)
Two Star Challenge – Drum Magazines (large magazine ammo)
Parkour This Challenge
One Star Challenge – Front Grip (increases gun accuracy by reducing recoil)
One Star Challenge – Rapid Fire (increases rate of fire)
Two Star Challenge – Silencers (makes gun firing less audible)
Tower Defense Challenge
One Star Challenge – Adjusted Iron Sights (disables zoom on iron sights to increase peripheral awareness)
One Star Challenge – Underslung Grenade Launcher (grenade launcher barrel attachment)
Two Star Challenge – High Capacity Magazines (larger magazine ammo)
