Interesting. Still deadly at contact distance.
I still recall that in the late 90's, after a couple of shark attacks within a couple of weeks, that urchin fishermen at the Channel Islands off CA started diving strapped with Glocks. The commie pinko local rag had a bunch of stories and photos regarding the armed divers.
A bang stick would have been much more effective, but I understood their thinking, what with having their hands full with urchins and stuff.