The US mint mints coins with them every year for several years now.
I know, I have bought many things from them this year. I am in process of buying every silver proof set.
Recently I bought a 1951 proof set. I now have 1951, 1953, 1955-1964, when they went to clad. I am also buying 1992 and later silver prrof sets when they started making them again.
I hope to have all silver proof sets from 1950-1964, and 1992-present by this time next year.
And yes, I do have the sets with the 40% Kennedys also, along with the 40% Ikes.
I even started posting on youtube some of my aquations.
https://www.youtube.com/@packratcollector