The 1940-S has the distinction of being the worst struck of all the Walking Liberty Half Dollars. The typical 1940-S is very weakly struck at Ms. Liberty's left hand with many specimens showing no hand detail at all. The phrase "flat as a pancake" is very appropriate for this issue. Decently struck examples do exist, but they are scarce. The 1940-S is the rarest Walker of the 1940s in both uncirculated and Gem condition. It is quite a bit rarer than the more highly touted 1941-S. The 1941-S gets more attention because of a holdover from the days of coin albums when the Walking Liberty half dollar set came in two albums, the 1916-1940 issues in one and the 1941-1947 issues in another. The 1941-1947 albums were know as the "short set" and the 1941-S is the rarest coin in the "short set," hence it's popularity as a late date Walker rarity. However, the 1940-S is definitely rarer.