I never knew they rejected coins prior to 64 that had no defect. As a matter of fact I have read a few threads on this forum of people who were CRH'ing by buying the bags of coins from the person who maintains the coinstar machine. They said they found silver in them.
It does it by weight just like those sorters that separate zinc pennies from copper ones.If they didn't all the canadian coins would work because they use the same size we do.And people would be hammering out lead quarters from buckshot.Just like you can't copy a dollar and feed it through a bill changer