I've been find a lot of coins but not much deep coins and silver. I'm digging mostly 32 plus numbers. Twice I have dug some deep rusted iron that read rock solid numbers one was 37 and the other was 17 (which I thought was a nickel). These items read the same at the surface until they dried.Then they read -10 and -7. I'm thinking deep coins in wet ground may read different also.I was wondering if anyone else noticed this? Looks like I've got some digging to do.