Late Level Loadouts
The Javelin is a good weapon in many maps, and Desert Eagle is good when facing tanks, wearing out their iron will. Ammo Mastery makes up for the low ammo of the Javelin, and why not fill the whole map with bombs? Note: Air Strike is only available on outdoor maps.
Note: This is best used against the Globex Leader.
In Campaign: The Final Showdown, this is the ideal loadout to use. The Globex Leader would be vulnerable to the Minigun, and you can camp on one of the MiGs and if the Globex Leader gets in vision, shoot him due to the long range of the Desert Eagle, Ammo Feed gives the Minigun no time to reload, and since you can get killed easily, Bouncing Betty would do the job with 2 kills.
This is an ideal loadout for Quick Matches. The AUG in particular is basically a high-capacity, high-damage sniper rifle if used correctly. Add to that more ammo, a high-accuracy SMG and a mastery of choke or spawn points will make you a master.
Early/Medium Level Loadouts
AUG HBAR + Skorpion + Ammo Mastery or Ammo Feed + Bouncing Betty
Since the AUG has a small clip size of 30x4, Ammo Mastery makes this irrelevant to the weaknesses of the AUG HBAR. The machine-gun has an accuracy of 80%, and its slow fire rate of 6rps helps a lot with the accuracy. The Skorpion has a fast rate of fire and useful against tanks with iron will.
The Saw could cut through enemy lines with its fast fire rate, but due to its low-moderate ammo, Ammo Mastery could do the job. The Beretta could be used as an alternative for an SMG or Machine-Pistol, since the Saw is an automatic weapon. Surge would make you take 30% less damage and deal 30% more damage. This is useful when attacking a group of enemies on your own.
The Stinger has homing missiles, good in the Foundry or Speeding Train map, if you aim from the top of the map. When an enemy wants to get up close, you can use the patriot, because of it`s high rate of fire and is better in close-quarter encounters than the Stinger. If you die while reloading, Martyrdom can take out nearby enemies, good for fighting a melee Assassin but not good for snipers. Tear Gas only requires three kills, so if you get lots of kills with the Stinger you can keep the Tear Gas almost constant.