Ron Guth: The 1842 Half Dime has a relatively high mintage, but it is far from being the most common date of the 1840s. Nonetheless, it is normally priced as if it was, so there is possibly some value baked into this date. By definition, that makes the 1842 a sleeper.
This date is encountered most often in MS63 and MS64. Gems become very scarce and none have been certified by PCGS finer than MS66. The highest recorded grade for the 1842 Half Dime is MS66+.
Under normal circumstances, the 1842 Half Dime is well struck. If there is ever any weakness, it is seen occasionally on the denticles on the obverse and, less seldom, on the obverse stars.