Google tells me a .50 cal can take out most choppers if it can hit them, and severely damage an apache.
An Apache with 2 engineers flying can only be taken out by 3 ground engineers with added antiair support to soften it up.
no one else can even slightly damage it.
But the engineers have the crappiest rifles, especially that Krait piece of c***.
I'm a level 15 engineer and I only use the beginning SG and occasionally the genesis.
But yah, Apache is overpowered or doesn't take enough damage from other rounds.

Quads should not do endo's after jumping. A human can keep a quad stable and upright when they get big air, and a tiny rev boost by pressing x or y would help make it more realistic. Quads also start up too slow, real quads are snappier and turn faster and sharper.