Hi James,
The reason why the Gradients doesn’t follow the same effect on the Caps is because the mesh topology in the Cap is different from the rest of the Sweep, so to overcome this you need to change the the material projection from the UVW Mapping to a projection suitable for the Sweep shape here such as spherical or cylindrical so that the application of the material will not be related with the topology but with the shape as a whole and then you can control the projection through the Offset, let me know if this works for you.