I was always curious why the US Silver 3-coin Proof Set coins dated 1776-1996 were only minted in 40% silver. I know of no other US coinage minted in 40% silver. Any reason?
Also, I believe Kennedy Half-Dollars minted from 1965 to 1970, and 1976, as well as Eisenhower Silver Dollars minted in the years from 1971 to 1974, and 1976 were 40% silver. Also war nickels were 35% sometimes clumped into the 40% category. There may be others too ... from USACOINBOOK.com
https://www.jmbullion.com/ultimate-guide-to-40-silver-coins/ Between the years 1965 and 1976, two major U.S. coins contained 40% silver. The term “40% silver” is a short way for investors, collectors, and buyers to refer to Kennedy Half-Dollars minted 1965–1970, and 1976, as well as Eisenhower Silver Dollars minted in the years 1971-1974, and 1976. The term also serves to differentiate these coins from pre-1965 coinage, which contained 90% silver, as well as currently circulating coins, which do not contain any silver. A 40% silver quarter dollar was created for the United States’ bicentennial, but it was only available in Mint or Proof sets; it was never in general circulation.
That quote makes me nervous, because: a) It doesn't indicate that there were clad Ikes as well b) It points out that 40% quarters weren't for general circulation, but doesn't indicate that the same is true for 40% Ikes (and 40% 1970 and 1976 Kennedys)
