Why does my weapon have a mysterious offset?

Hello!

I have been setting up my firing for a while, but there is one bug I can’t explain.
-when facing towards negative y/x, the shots go way off from the center of the screen. When facing towards positive y/x, the accuracy seems completely acceptable (looks like debug nodes are triangles, and if the triangle was mirrored forming a square, then origin of that added triangle would the center of the screen. Can’t understand why didn’t they make them round/square, but anyway).

Here is the blueprint. The way I calculated the end point comes from some dodgy answerhub page, but it seems to work (at least on positive x&y).

Hoping for answers, -DoctorPC