Mission 3: ReactorIn this guide I found 2x Bomb Drones, 1x Cruise Missile and 1x Precision Airstrike worked in getting my achievement to pop.
Bomb Drones:Parachute into the Mission head North East towards a supply drop tangled up in a electricity pylon, where you'll find the first Bomb Drone. Now head South East to a white/blue cabin where you'll find a second Bomb Drone. Use both of these on the closest helicopter to the East.
Cruise Missile:Directly behind you to the West, beside this blue/white cabin is another supply drop with a Cruise Missile in it. Immediately use this Missile to take out the helicopter on the West side of the map.
Precision Airstrike:Now head South towards the last helicopter, the large hanger to your left has another supply drop hanging off it (beside the letter "A"). This drop has a Precision Airstrike in it, pick that up and use it on the last helicopter in front of you.
Long Rifle Mentioned: It wasn't tracking for me at first but I realized after you pick up your first kill streak you have to wait about 1min and 13seconds till a pop up on your screen says "press
to use armament". After this I used the kill streaks and they tracked correctly.
Video guide: