As a grown man in his late fifties I felt kinda silly doing this but it was more fun then going to work today so after I finished my yard chores I decided to air test some of the zinc pennies and pull tabs that I have found in the last couple hunts with the Manticore. I'm not skilled enough anymore to up load a chart on the internet but you can get an idea by looking at the numbers. Zinc pennies and pull tabs are a problem for those of us that chase gold rings out in the wild.  strick