I've been trying to figure out how the rim cud could happen on this silver dollar. Was this done by a machine while it was being minted and is it a real error or am I assuming too much?
I have never heard "rim break" before. I have always known it as a rim CUD, as a CUD is a die break that is attached to the rim. For instance, coppercoins.com states that for the 1972 DDO die 4: