I agree with the other views here that the newer high sensitivity machines will have problems with false signals over trash, especially Iron. I have also felt that when a detector coil is swung over a nail, you are inducing a small magnetic field around the nail and and by its physical nature, the magnetic poles are at each end of the nail, where the detector seems to pinpoint over. Not that big of a deal, really, except when your sensitivity is set real high to process those super-deep faint signals, it will also start producing positive results over the faint junk signals. Still, in most situations, the iron falsing can be sorted out from the good target signals with practice and proper tuning of the detector. HH, Mike.