Mintmark style of the 1946S ball seriff, with flat spot on lower ball, looks like this http://varietyvista.com/01a LC Doubled Dies Vol 1/San Francisco Mintmark Styles.htm and the inverted looks like this with the ball at bottom and flat spot at top. http://varietyvista.com/01a LC Doubled Dies Vol 1/1946SIMM001.htm Wear and a deteriorated punch could allow for the fat upper part and loss of detail on the lower part of the MM. JMHO, and I might not be aware of other varieties.
