Went hunting today with the ace 250 and big coil.The way it looks like i was digging junk not so.Most of the coins were in what you see only 3 of pull tabs fooled me.The button was at 9 INCHES,the coins in the junk were all around 6 to 8 inches,the other coins from 4 to 6 inches. custom and all metal mode sen. around 6 to 7.This is what i say about sniffing out a coin in iron and junk you can get the tones to separate by wiggling the coil back and forth about 2 to 3 inches and walking around targets you will start to hear only the coin.Good luck and good hunting