That must be a Very Powerfull Magnet. And I suspect that the steel coins will not last long in the ground or on a beach. And I doubt if I would ever find one as I usually ignore iron/steel signals.
But with USA nickel composed of 75% copper you would thing they would register higher than they do.
I am going to be doing some test to see where the 99.9% nickel coins show up on my detector
Thats odd, I've got a 1975 Canadian dime that is 99.9% nickel and on my F5 its all over the board, goes back and forth from iron all the way up to quarter. Good thing I'm not looking for any of that Canadian money