Mox,
Sorry we couldn't hook up on Sunday. I was pushin dirt all day.
I've had my GB2 a couple of years now and still learning.
Dial down your Sensitivity knob to about 5 to quiet it down some in noisy areas.
Old iron will chirp on Iron Disc., take some lead to drop on the ground once you ground balance for an area to get a tone for it. I used to epoxy a split shot weight on the end of a chop stick with 1" marks on it. You could push it in the ground to see what sensitivity depth you have based on the dirt you are standing on.