the park i hunt is loaded with pulltabs bottle caps one day on way out set machine 20 fer 30 co sens 28 had no thersehold nulled out most of the time i found 4 inch deep merc thought it was luck tried next time same story so 6 silver dimes later with that setting is it luck or what the numbers will not always read right go mostly by sound also there is alot of erorsion in the areas i focus on have not found nothing deeper than 5 in doing this tonite another merc 2 wheaties might work for you try it