Found a Merc today. I hunted along a bluff in a wooded area of the local park. Using a Vaquero with stock coil I heard a faint signal underneath a fallen tree . It sounded sweet but disc'ed out a little past tab , so I was expecting a lead bullet . About four inches down on the side of the hole was a 1936 Merc. I had the machine set with minimum disc sens a little in the red and threshold at 1 o'clock. Those are my default settings in untrashy areas . Also found a real nice square nail and cork bottle .