1917-S Walking Liberty Half Dollar. Reverse Mintmark. MS-64 (PCGS). CAC. Impressively sharp for an S-Mint half dollar of this type, this premium Choice example also offers full satin luster and virtually brilliant surfaces. With Gems of the 1917-S Reverse rare, this CAC-approved MS-64 represents excellent value for the astute bidder. PCGS# 6573. NGC ID: 24PU.