These weapons are obtained by successfully completing tasks in the Spec Ops missions.
G3
- Kill the sniper on Tower One in "Hotel Ambush".
M16A4
- Kill all enemies without being detected in first two areas during "High Value Target".
AUG A3
- Defend one of the towers without killing any teammate bots in "Hill 137".
M60E4
- Kill 5 enemies in <4 seconds and 15 total with grenade launcher in "Oasis Village".
SVD
- Don't get hit when crossing 2 open areas when defending the bunker in "The Brecourt Bridge Defense".
SCAR-H
- Kill 3 RPG soldiers from the first building you take cover behind in "The Last Resort".
FN P90
- Kill the first 15 enemies without killing any civilians in the first part of Panama Canal level in "Uprising".