Quote Originally Posted by Retro00064 View Post
Thanks for the drainage system patent. I never knew that Master started making locks with such a feature before, and learned something new from this thread! I looked at some of my locks and it seems that other Master padlocks were made with the drainage system too: my circa 1960s Master "Super Security" #81 (their first padlock to have a 5 pin cylinder, I believe; any knowledge of what year that one was introduced, BBE? :-), a circa 1980s #15 (of a similar vintage to your #19), and some other standard pin tumbler models from the 1970s to the 1990s have a small hole at the bottom of the receptacle for the shackle toe in the lock bodies (clogged up with dirt in the more heavily weathered ones), which may be a drain hole, while some 1990s #5 padlocks of mine have a huge hole.
I don't seem to have any dating info on the 81, but the 15 was introduced in 1968.
BBE.