This is a reopened issue. I was told that this is not a bug but I beg to disagree. I'm submitting it again because of the new information about trees.
Just a thought. The 20 mm gatling cannon in AH-99 takes about 150 rounds to cut down tree, although it's harder to keep on target. I think the hit % was about 70 or 80 %. And it takes about 50 rounds with 20 mm to start destroying the control tower and total destruction with around 100 rounds. And those rounds are high explosive.