FOV calculations in BP's

I am working on an Arena FPS. I have a material function that modifies the FOV of the guns and arms so that they always appear to be the same FOV no matter what the camera FOV is.

My question is does anyone know how I can do the calculations in Blueprint, so that I can feed in a world location and get back a world location that is adjusted to the FOV. I would like to spawn things that originated from my barrel, but because of the FOV and material that changes locations. Anyone have any ideas?