It depends on the soil, and whats around the target. Also, what's on the target. You'll find a silver quarter will ping at 1-49, 11-47, 12-47, 12-49, 1-46 etc. You just have to realize that it's rare you'll ever get the perfect numbers. They just don't exist in the field unless you happen across a coin flat on its back, shallow, and in clean soil. What you can see from the examples I gave, is that the Fe numbers are in the sweet range for a coin, and the Co is in the silver range also. You would dig any of those combinations. You'll also learn what a long squelch sounds like when you slowly slide over a crushed can, and the difference between that and a coin. The numbers are almost identical and you'll get fooled in the beginning.