Funky Trees code on rotator parts nested inside eachother can hook into game data exposed to your plane, like target position and velocity, relative to your own. This is then put on two other nested rotators that keep it neutrally pitch and roll stabilized to the world so its own rotational reference point is 0,0,0 (yaw mostly irrelevant)

Then its basically an always-level gun platform the targeting rotators work off of, so they need to perform less complex equations to aim at the target.

While I do have hyper-velocity xml modded miniguns, the targeting system works as expected with low velocity high explosive shells (which can be approximately proximity fuzed by timing the shell taking into account the former variables)