Mission 5: Kunlun Mountains
Weapon 12: 338-Recon
Once you finally reach the snowy outdoors, make your way up the hill and as you go to cross the large bridge, take the stairs down and underneath the bridge will be a catwalk where the weapon will by lying in the center.
Mission 6: Tashgar
Weapon 13: A-91
Before you go through the archway to enter the second area, get on the roof of the blue building to the left and hop across to the roof to the east. At the corner of the building you will find this weapon lying on the edge.
Weapon 14: M249
As soon as you enter the park, go west of the first weapons crate you come across and to the right side of the destroyed car there, you will find this weapon on the ground.
Weapon 15: AEK-971
Just after the park and through the tunnel, you will enter an area with a large building near the center to the right. Head up the stairs and on the third floor you can access a roof area. Look for the green crates there and the weapon will be leaning against them.
Mission 7: Suez
Weapon 16: AK 5C
Near the start of the mission, you will run forward across the deck and be attacked by swarms of enemies. As you get farther up, the tower of the ship will fall over to the left side onto the deck. The weapon you want will be under the tower, but it won’t move until you clear out all the enemies that are present. Once they are gone, the tower will slide off and the weapon will be lying on the deck just in front of a fire.