A railroad rim has nothing to do with die alignment. The it is a nickname for the error called a partial collar. The collar does not come up completely around the outside of the coin to form the edge. The result is the edge of the coin will be the correct diameter on part of the thickness and will be larger on the other part because the metal flows out where it is not contained by the collar like it does on a broadstruck error. When you look at the coin from the side it resembles a railroad car wheel with a flange on one side. That is where it gets its nickname.
Oops. Bryan beat me to it. He must type faster than I do.

Edited by pyrbob
10/03/2010 5:41 pm