I've tried and tried to beat the Choppers at the Dam after exploding the Jamming device.
I can destroy one of them with my Hand-Held Heat-seeking missile but, I can't seem to get the 2nd one.
My team members are carrying the same weapons I am but, they just shoot at the Chopper with their guns.

Any help would be greatly appreciated.

Thank you,

Yeah noticed this myself....tried putting my men on Assault mode and having them shoot the helo down but to no avail...they move out of bunker, grab their LMG and light up the sky with ineffective fire and usually get blown away.

Myself, I have picked up one of the heavier machine guns from fallen foe and tried to duck/hide and scoot to shoot the last helo...usually what ends up happening is that my guy gets killed while standing inside bunker from the penetrator missiles this helo uses...and it doesnt matter where I am...those missiles will penetrate anything...even walked back to the power plant and was standing inside where nothing could be seen near the generators and boom! I died....guess the helo has mountain penetrating missiles....its becoming frustrating to keep playing this stupid level and not getting anywhere....the most I can get is the helo to smoke after putting in about 2-3 mags worth of shots...but eventually he kills me while Im taking shelter in bunker

Did it ... as you figured out you can take out one with your IR missile. If you're luckily and a good shot you can take one out with an RPG you may find laying around. I personally did the heat seeking missile - then picked up a LMG and would watch the helicopter’s green target box ... as soon as it appeared to be overhead ... I shot at it's belly and back side. Almost right away it'll start to smoke. As you damage it more and more it'll start to smoke from the tail. Soon after it'll pop.

Hint: before you plant the EMP device - place any remaining guys up on the roof of the building at the helicopter pad is at. Once you detonate the EMP and start moving in that direction - the enemy that pops up on the roof will be sitting ducks for your guys making you escape easier.

One note.... after having done all this successfully I've trigger a bug I think. The 2nd helo went to the bottom of the water at the dam without getting destroyed ... so I'm now stuck.

Hmmm, interesting, I destroyed one with my heat seeking missile, then clicked on my team member who was carrying another heat seeker, scrolled down to 'attack' and clicked the execute button and BOOM down he went!! This execute button is assigned to MOUSE button 2, which most of us don't have. I just assigned it to another button. Anyway, it worked for me, try it!~