In 1971 there was some 40% silver half dollars made by mistake and in 1977 it happened again so I was wondering if there was any 1972-1974 40% silver errors done? I know the U.S. Mint made some 40% silver half dollars for Panama from 1966-1972 so is it possible some of those silver blanks made it into our coinage in 1972? Picture below is a 1971 40% error half dollar, does anyone have images of a 1972-1974 40% error half dollars?
The Panama coinage was made using the same planchets as US coins except the half balboas in 1971 and 72 which used the 40% silver "half dollar" planchets. But those half Balboa planchets being used to strike half dollars in 1971 or 72 is unlikely as all the Panama coinage was struck in San Francisco, and all the 72's were proof coins. There is a small chance that the 40% silver planchets may have accidently gotten mixed in with rejected copper nickel proof planchets that were shipped to Denver for use in making business strikes. It is thought that that is how the 40% 1974 D and 77 D coins were created, rejected 40% silver blanks accidentally got shipped to Denver mixed with rejected CuNi proof planchets.
