I have been trying to find out what RPM # this 1920-S it is. I have hunted thru Coppercoins.com but its not listed. Here the coin.
I found a Wexler RPM-001 on Doubledie.com. The diagnostics are fairly close, the bottom line "S" sits to the north and yours looks to be that one. But at the same time yours looks to be to the west too. Nothing in Cherry Pickers or any of the other sites. -Shaun