which us coins are 40 silver

[LaEthan]

Hey there! That's a great question about a really interesting period in US coinage history.

Based on the information, the primary US coins that contain 40% silver are the Kennedy Half Dollars that were minted from 1965 to 1970. After 1964, when the US stopped making 90% silver coins for circulation, these half dollars were the main circulating coin to still contain a significant amount of silver.

Another key coin with 40% silver content is the Eisenhower Dollar, specifically those minted between 1971 and 1976. These are often referred to as "Ike Dollars." It's important to note that only certain versions of these dollars, primarily the uncirculated and proof versions intended for collectors, contained the 40% silver.

Additionally, special Bicentennial collectors' sets from 1976 included quarters, half-dollars, and Eisenhower dollars that were also produced with 40% silver. These coins are often called "silver-clad" because they were made with an inner core of a silver and copper alloy, bonded to outer layers of a different silver and copper blend, resulting in an overall composition of 40% silver.