Jim,
I'm still practicing with iron check. So far with what I can tell it is not geared for small iron as to not loose small gold. 3" nails it does just fine on, but small stuff you still got to dig. Boot tacks, small roof tacks will not iron check with iron grunt, but the sound of an iron target is not a smooth as a low conductor. More test coming soon. I have not messed with any discrimination as of yet...as I'm digging everything to get used to the machine. So far, both with the stock 12" coil and the 8" mono coil easily hit .1 gram nuggets. More soon...