I personally think taking down a chopper is easy with a gun I made a mission where some AH-64's fly over and shot at stuff, one was hovering, a few shots and BAM the gunner is dead, another 10 shots and the pilot was dead. I also shoot down choppers with my machine guns in missions where i screw around. I have never tried to take down a MI24 though. Once I fired a short burst at a MI-17 but didnt really care about killing the pilot.