Hey John,
I think that if you change your iron mask from -10 to -15, you will be able to hear those iffy coin signals better. You will be able to hear the coins better that would be otherwise masked by nearby trash, and you will be able to hear the coins that give off iffy signals because they are super deep. Your machine senses the target whether you have ironmask -10 or -15. But with -10 you will get more nulling from an iffy signal than with -15.
Discrimination does not reduce your depth. For example, I saw my buddy richard find some 8 inch deep coins with the 7.5 inch coil while he had heavy discrimination going.
The main factor that affects your depth is how much trash is in the area and how deep that trash layer is. If you have a dense trash layer at 4 inches deep, you will not hear a dime at 8 inches because the dime signal is overpowered by all the strong trash signals.
Also, watch out that you do not have too much sensitivity in trashy areas. If your sensitivity is too high, the trash will block out coin signals. You have to turn your sensitivity down until the signals don't sound like sticky splats.
Mike
