What Smokey said, see my post in another one of your threads. With EQUINOX its really tone that tells the story...
But if you are a glutton for punishment:
Buttons are mid teens
Non-fragmented minie balls are high teens
Eagle Breast Plate you are looking at in my avatar mid-to high 20's
Big Blob of melted aluminum slag - mid-to-high 20's
Oh, and all those numbers changed once the relics are out of the ground.
I was really looking for repeatable signals, in rough vdi ranges, with good tone and digging. The tones and not the vdi helped me to recognize the difference between the aluminum slag and the breast plate. But I had to dig aluminum slag to figure it out. Don't ask how the aluminum slag got there.
Going from memory. I don't take very good notes in the field, too busy digging.