Based on the press release it sounds like you might already be planning to do something similar to this:

First building: barracks: standard infantry unit.
Second building: Armory: armory allows all your infantry squads to attach another specialized person such as:
Grenedier: M203
Designated marksman
Support gunner: SAW
Anti-tank: hand held rocket launcher.

The Armory would also deploy mortar teams and MG teams (do these exist on the modern battlefield?)

O wait, im an idiot, this is basically the wermacht grenadiers without the added man. o well, just an idea.

the mg is the SAW

MG gun is the General Purpose MG which is designated the M240 by the US army.

Where as the squad machine gun aka Automatic Rifleman is the FN Minim which is designated the M249 Squad Automatic Weapon by the US army.

Then you also get the Browning .50calibere M2HB Heavy Machine Gun used by machine gunners of fixed positions and vehicle.