[Contagion]

The MGNM AM spec makes bullets more deadly. It is kinda like the Stopping Power perk from MW.
Level 13 required to unlock. I hit 13, no unlock. I hit 14 it says I need to be a Battlefield Veteran. I am one..
There are other specializations that are doing this as well.

 

[bluepiglet]

the descriptions of some unlocks are wrong. you will have them on a higher level. being a veteran will lower the required level. but don't worry, even without being veteran, you will have all the specializiing options opened before level 20.

 

[Schizms]

I got the MGNM ammo at lvl 15.

 

[melterx12]

yep it unlocks at lvl 15.

 

[elson]

me too at lvl 15