Collect the indicated number of badges to unlock the corresponding bonus:

Adjustable scopes: 6 badges
Paramilitarty Light Weapons set: 9 badges
Paramilitarty Heavy Weapons sets: 12 badges
Defense Force Weapons sets: 15 badges
Jukebox - Main Theme: 15 badges
Jukebox - Kariminal: 15 badges
Jukebox - Boomer's Reprise: 15 badges
Jukebox - Catch and Release: 15 badges
Rebel Weapon sets: 18 badges
Jukebox - The Infinite Soul: 21 badges
Jukebox - Fireteam Bravo: 21 badges
Jukebox - Urban Destruction: 21 badges
Jukebox - Band and Clear: 21 badges
Jukebox - Roll Over Adjikistan: 21 badges
Jukebox - Credits: 21 badges
Mercenary Weapon sets: 21 badges
SEAL Weapon sets: 24 badges
R44M Gun: 27 badges
Enemy Explosives: 30 badges
MM-I Grenade Launcher: 32 badges