I am having an annoying problem with my front brake. Its a juicy 3 caliper with a 203mm rotor.

When Im cycling and have to brake hard for a prolonged amount of time, maybe a sharp decent or long hill at the end when I take pressure off the brake i get a rattle.

I have taken the pads out and put a but of copper slip in the holes where the piston sits but that has just muffled the rattle.

Is there anything else I could try?