I'm not a handloader deaf, would a 10mm work almost as well? It seems to me the only realistic scenario is using the energy of the round to break ribs/ cause internal damage. First hit breaks the rib. The second in same area shoves the jagged rib into what ever is behind it. You hope.
Gaily bedight, A gallant knight In sunshine and in shadow, Had journeyed long, Singing a song, In search of El Dorado