Great Thread! This is interesting.
An interesting though somewhat unrelated fact is that a classic Inuit technique for taking full grown moose is to "take them out" while they are in the process of swimming across a body of water.
They paddle alongside the swimming moose & "instantly turn them into food" with a single close head shot from a .22 rim~fire handgun.
The little short barreled Stainless S&W .22 "kit gun" revolver is a favored handgun for the task.
Years ago they even used the .22 Short.
For defensive shooting a well placed "head shot" is hard to beat for instantly putting a stop to a deadly threat.