Why does my machine reject some wheat pennies?
Check out this chart… it shows why some old Wheats are rejected. They have “mixed” alloys and the sheet stock the mint used was not purified enough. When using a newer sample coin, the machine is comparing the moving coins against the reference coin. If they do not match within a practical window of acceptance, it will reject the coin.
These coins were originally "rejected" by the Ryedale with a copper alloy reference coin installed. I was curious what was going on, so I used an XRAY Flourescence device to measure the metal content/blend in each coin. I think you'll find this chart interesting, as it shows that the coins have a wide variety of elements in the mix.