Have you tried open screen all metal ferous with 2 tones as I have had good success with hardly any false signals and very little nulling.I have been in some very trashy sites and it works for me just have to check the numbers if looking for coins but if relic hunting I would think you would dig any solid signals that are high or not low iron.When in a junky park I have also found that when I get a high tone if I switch to factory coin pattern I can get a better or more accurate digital number lock even when next to iron.I did dig a nail that acted like a coin in every way,it was 6" deep and was strait up and down with the head up.It was about a 12 penny size nail and quite rusty.I to miss that nice high flute sound in ferrous that was better than any digital numbers.