Wish I had better news. Its a little off location. Way off the size and shape for an O. I think its just damage on the coin.
for comparison, here is a current auction for a 1851-O:
http://www.collectorscorner.com/Pro...?id=27928745
for comparison, here is a current auction for a 1851-O:
http://www.collectorscorner.com/Pro...?id=27928745






















