Thanks for all the great comments!
I use many shades of Alclad Paint. In that case, it's a base coat of "Steel" (or Magnesium, both are close), then Exhaust Manifold (this color give the whole "dark bronze color") then finish the extremity with Burnt Iron with a few accent here and there. You have to use an airbrush for this, but Alclad paint are really great to work with!