a friend wrote:


according to Feynman's book, these were padlocks, presumably the early
Sargent and Greenleaf type - the later ones had some anti-tamper
features but the earlier ones could be felt out, at least for a few
numbers, limiting what you had to try. go to a surplus store and buy a
bag of these locks, they are deprecated now.

Master padlocks are easy. But, I am SURE he was referring to
secure file cabinets and safes at Los Alamos during the Manhattan project.

Jon