G load does not effect bullet drop. As soon as it leaves the muzzle, it is in 1g trajectory. Turning target causes the illusion of dropping bullet.
Exactly. However, any deviation in angle of attack will affect the external ballistics of the projectile.

This F-16 is in 1G level flight at the edge of stalling with an extreme angle of attack. The F-16's velocity vector is easily observed by looking at the wing tip smoke. Equally obvious is the extreme deviation of angle between the F-16's velocity vector and the 20 mm gun it carries. If that F-16 were to fire a burst it would drop a lot more over distance than if the plane was in level flight with a much lower angle of attack. The F-16's velocity is added to the 20 mm shell's velocity at an angle and thus changes the vector of the shell + all the other secondary effects I mentioned in my previous post.
To produce G an aircraft must increase the angle of attack and it is this deviation in angle between the direction of flight and the gun barrel that causes the increased bullet drop. The increase in G is also just an effect that follows the increase in angle of attack,
but this relationship is not linear. How much angle of attack is needed to produce the desired amount of G varies with speed. So a 2G turn at high speed requires a much lower angle of attack than a 2G turn at low speed.
In some aircraft like the Fw 190 the angle of incidence of the wing (the angle between the cord line of the wing and the axis of minimum drag along the fuselage) combined with a high-lift wing profile creates a situation where the aircraft is actually flying in a nose-down attitude at high speed. Allied pilots remarked how strange the 190's nose-down attitude looked when they first encountered it. This creates a reverse of the effect when trying to shoot at a target flying straight and level as your guns are actually pointing downwards compared to the aircraft's velocity vector (flightpath). I.e. if the target is in your sights and is flying straight and level you are either in a slight climb, or the target is slightly below you.
Dropping a bomb and firing a gun from a plane is essentially the same thing. The only difference is that you give the bullet some extra push down the barrel in a given direction. Both the bomb and the bullet are affected by the aircraft's velocity and velocity vector at the time of release/firing. The bomb gets all of its velocity and direction from the aircraft, while the bullet also gets a velocity and direction from the gun it is fired from. When these two are not in alignment strange things happen.
I hope this makes sense to anyone. I'm not a very good teacher.