The explorer series are not designed for nuggets. As you know, most nuggets found in nature are grain of rice sized, at the very biggest. Nuggets larger than that are very rare. In fact, a lot of nugget guys are litterally chasing pinhead and flake sized nuggets, with machines designed expressly for that purpose. The explorer, on the other hand, is designed for coin/relic/jewelry. And the goals of each venue are opposed to each other, when you think of it. A coin/relic/jewelry hunter doesn't necessarily want to hear every pushpin, birdshot, staple, etc.... And for a machine to get extreme depth on pinhead sized targets, it has to for-go iron disc. The coin/jewelry/relic guy doesn't want to for-go iron disc. The the various machines are designed, from the bottom up, for their express purpose.
There's been a few attempts to make detectors which can switch back & forth between tasks. But they excell in neither arena. There will be better coin machines, and there will be better nugget machines.