There were only three issues of this series struck between 1921 and 1929...the 1923-S, 1927-S, and 1928-S. All three coins are scarce in higher grades, rare in mint state condition, and very rare in Gem condition. The 1923-S is somewhat rarer than the other two in higher circulated grades. It is definitely the rarest of the three in mint state and Gem mint state condition.
This is the first issue in the Walking Liberty half dollar series in which strike can be a definite problem. From here on out...until the last S-Mint was struck in 1946, most of the S-Mint Walkers have weak stirke problems, some severely so. It is not unusual to find mint state 1923-S half dollars that are very weakly struck on Ms. Liberty's hand and the central devices on the reverse. Examples that are relatively sharply struck are hard to find and well worth the premium price they often bring. Luster can be frosty and there are many mint state survivors that are toned.