“A shotgun lets you bleed to death slow.”
Not at all correct. The advantage of a shotgun is the production of multiple wound channels. For that reason, #1 buckshot is recommended over 00 or (my old favorite) 000 buckshot).
There was a reason White Hunter going into thornbuch areas after wounded leopards preferred a double barreled shottie, with two triggers. Both barrels were fired when Mr. Cat jumped out of concealment. The White Hunter chose 00 buckshot because of a greater need for penetration than is needed for gun fights with unarmored humans.
Shotties cause quicker incapacitation from blood loss and tissue damage than rifles and handguns.
It depends on the distance. If you get a straight shot up close and personal the head comes off. If you get him running away you might put a bunch of small holes in him and it will be a slow thing.