The basis of this seems to work:
You’ll have to excuse the debug wires, but on the weapon you’ll get the owning player’s controller and use it to rotate a vector offset you define per weapon, then add the location of the actor. It will need refinement, the dubug arrow and sphere are useful to see the inaccuracies.
e:
I had some time for more testing, this is now implemented into my own project.
Similar to before but with more reliable results that replicate in my own project. The branch in the function nulls the offset for ADS.