Tank / turret animations

I don’t know if this question is more of Blender / 3D or gamedev / Unreal question, but I decided to ask here first.

What I want to do is make a character, simple robot. The bottom part rides around on wheels, controlled by keyboard, while the top part is a turret that turns towards player cursor (which works as a crosshair).

I made the model in blender, using only two bones, one for the bottom part and one for the turret. I created 4 poses for aiming each direction.
Then, in Unreal, I created 2D aim offset (as I only need one dimension). And after some coding, it works… almost. When I aim forward, and then to the right, it transitions, nice. Then towards the back, also works. But if I then move to the left, instead of rotating extra 90 degrees, the turrent rotates back forward and then to the left.

How can I fix it? Is there some settings in Unreal that I could use, or should I create the model in blender differently? Is the whole rig / bones solution not gonna work?

TLDR: I want the turret on my robot to rotate infinitely to whatever I aim at.