Call of Duty: Modern Warfare 2
The AA-12 is unlocked at level 18, and it is arguably one of the best secondary weapons in the game due to its high rate of fire and power.
A major disadvantage is the lack of ammo the gun possesses (16 shells, without Scavenger Pro). With Extended Magazines, which is unlocked after getting 400 kills with the weapon, the magazine size is increased to 16, allowing the player not to need to reload. However this gun will eat through ammo and therefore Scavenger is a recommended perk when using this gun.
It's also suggested not to use the silencer as an attachment as this will significantly reduce the range of the gun, which becomes useful as nothing more than a long knife!
Related ThreadsAA 12 Shotgun with HeartBeat Sensor - last post by @ Mar 21, 2010
Silenced AA-12 - last post by @ Feb 3, 2010
[75thR] Realism Unit AA&COD4 Wants You! - last post @ Apr 16, 2009
The launcher FHJ-18 AA and Smaw - last post by @ Apr 16, 2013
AA-12 question - last post by Whelan @ Oct 9, 2010