I was doing some research and came across the the very beginning of heeled bullet. This took the rimfire cartridge from a ball loaded into a rimfire cartridge (I believe invented by Flobert of France circa 1847) to a heeled bullet. I thought it was interesting. So I am sharing it. (You have to scroll backwards to see the drawings after clicking on the link)
https://books.google.com/books?id=oc...Stetson&f=true