Iron can be funny with the AT. Fragments read right at 32 and give a good sound I know what it is before it dig it most of the time. There is always the exception just like my partner dug what he thought was going to be trash and ended up being an eagle button face it gave a terrible sound he just decided to dig it, even 2 inches from the machine it was flaking all over the place. The cannonballs read 52 we actually dug them up when digging a footing and they were in the materials that were 5 foot down so I know there are more there just need to figure how to read them. The blade was only 2 inches in the ground and I could tell it was big iron and I just thought I had better see what it was I have left those readings before, you just never know but it was so big of a reading I just had to see what it was and it was in a confederate camp that had been hunted for a while. You know the old saying even a blind squirrel will get lucky but I digress. Digging everything can be very frustrating and take a lot of time that being said digging what you know is a good signal will up your good find to digging ratio but you leave some relics in the ground. I can tell you the difference in a button and a shotgun shell by the tone and I am right about 90percent of the time but I cannot bring myself the leave a signal like that. Small with foil cannot leave it. So bottom line go through a spot dig your really good readings then decide if the site itself warrants spending the time to dig everything. Good luck hope this helps Scott