I don't know how the gold tooth caps would work as substitute gold, but lead also works. The following statement is from a James McCulloch email I received.
<STRONG>For test "nuggets" use a #8 birdshot; no loss if you loose it, and if you find them with regularity you are doing everything right. They give about the same signal as a 1/2 grain nugget. When nugget hunting with your MXT, use the Prospecting mode, gain as high as soil conditions will allow, "ground" (tracking) ON, threshold BARELY audible, and SAT (dual control) full clockwise (maxed out). This smoothes out the ground, and makes small nuggets really "snap." </STRONG>
Jim is also an author of a prospecting book "Advanced Nuggetshooting".
Mike