Today I was running two tone ferous due to all of the junk iron and falsing I was getting. I did run the sensitivity to 29 and slowed down. I found several types of 4-hole buttons.
I also found several pieces of lead. The bottom right one in the pic appears to be a smashed Trantor. They all hit between 08 and 28 on the conductive number.
I only got to hunt for about an 1 1/2 to 2 hours so I am happy with the results.