Particle Size and World Units not the same?

For some reason, my particle size doesn’t seem to square up with my world unit size. In the image the blue ring is a particle. The material is just constructed using radial gradient functions, which always scale. The initial Size is 100 units in the X/Y

My Sphere trace has a radius of 600 Units.

When I construct my pawn, it’s particle indicates the movement radius it has, done so by setting the scale of the particle using the MV value in construction script. Having taken the MV Value, multiplied it by 2 and setting the vector value as this for the World 3d scale node, I would have expected the particle to end at the trace debug sphere.

Can anyone help explain why this happens?