I am fairly new to the etrac, probably 30 hours of detecting time. I went to one of my old favorite spots and found some good coins. A 1916 Barber dime, 1917 mercury dime, and several wheats in the teens. I love the etrac, but I need assistance. I occasionally receive signals that read 1-31 or 1-36 and they are showing about 12 inches deep on the depth gauge. I have dug a few of these and found them to be old nails and very hard to pinpoint. Is this a common thing? Should I be digging these all the time or are they signals of old nails? I would hate to be missing good targets. Thanks in advance for your assistance.