Jaime Hernandez: The 1976-S Uncirculated Silver Bicentennial Half Dollars were only sold by the U.S. Mint in a 3-Piece Bicentennial Mint Set for that year. Additionally, this is also a one year Type coin as the reverse design was changed in 1977.
In 1976 the Mint also struck three different circulation strike Kennedy Half Dollars, along with two different Types of Proofs. The other two circulation strike coins produced were the Clad 1976 P and D mint mark Bicentennial Half Dollars. Since the Clad 1976 P and D mint mark coins went into circulation, they are much more difficult to find in high Uncirculated condition. For the Proofs, the Mint struck a 1976-S Clad Half Dollar and finally, it also struck a Silver Proof version.