Blackstone
Brigadier
Using against chaff and defence is another thing. Able to hit it accurately is another thing that must be achieved first.
In 2002, Terrorism try to shoot down one Boeing 757 airliner and the SA-7 missile completely miss its target.
From Syria incident, you all can see, FN-6 is a very robust and accurate missile. Rebel with little training easily brought down the military helo. And mind you , from the video you can in fact, the helo is quite a distance from the firing point. I will say its near the max 6km of its intended range and it still perform flawlessly.
Long-range hits on the two helicopters were impressive, but they still were done under ideal weather conditions and against transport helicopters with no countermeasures.