Heckler & Koch
The MP7 is one of the last submachine guns you unlock, and it tears through most enemies. It fires at 950 rounds per minute and takes a full set of mods.
It is a late-game SMG for close and mid-range fights. Even standard rounds rip through most soldiers, and the high fire rate makes it forgiving when you miss.
Reach rank 11 and buy it from Juan's arms dealers, or upgrade the Guerrilla Garrison to level 3. FND Caches also drop it in the second half of the game.
Life Support has better accuracy but lower damage than the base gun. SMG-Issimo trades a lot of damage for handling and stealth. Second Echelon has slightly lower damage with base handling.
BP-SMG
The BP-SMG is a compact submachine gun that sprays quickly from a 30-round magazine. It is a good close-range stealth gun with a suppressor, and its unique Iron Curtain fires soft-target rounds.
BZ19
The BZ19 is a submachine gun with a huge helical magazine of 64 rounds. You can hold the trigger far longer than with any other SMG, and its unique Turn Of The Century sits at Resplandor Agriculture in Lozanía.
M12
The M12 is a Beretta submachine gun with a 32-round magazine and three fire modes. Its unique Five-Alarm version comes from an insurgency, and São Paulo Stinger is a customizable variant.
M249 SAW
The M249 is a light machine gun, labeled Tacticool in game, with one of the highest fire rates you can get. It is sold only through Lola's Black Market or the online store.