try it on editor.
Tested by placing an uh-80 to the taxiway directly west of the control tower and shooting at the control tower. Point of aim in the wall between the 1st and 2nd level windows. I tried it with an autorifleman too. He can burn through all his magazines without effect, but the uh-80 door gunner collapsed the building to first stage with as low as 26 rounds and completely to ground with less than 200.
The tree side. Place chopper close to (ca. 50 m) from a tree and have at it.