Theres a guy(cant remember name) that can pop off (6) single action shots in just over 1 second. He did some sort of splayed finger fanning on a precocked gun - each finger of the weak hand recocking it after a discharge on a wave of the hand.
The single shot shotgun is an easy one to do fast. I've been using singles since I was a kid. learned to break/grab&pull/drop/close&cock in a jiffy to get rabbits in FL.
Many people make the assumption that SA revolvers and double/single shot shotguns are insufficient for defensive(or offensive) use.. however they fail to realize there is generally 3 reasons why that person has one.
1. they are cheaper and thats all they could afford.
2. they prefer them and thats all they have.
3. they prefer them and they are better with them than you are with your techno piece.
Do you really want to find out which reason they own/carry/use such things?