Pat Garrett, Earp, Masterson, Wild Bill, and a bunch of others all carried single actions. They seem to have done fine with them. John Wayne also did fine with SA in his movies.
Love the Duke reference!
We have discussed this here before. Since I am a cowboy action shooter I have discussed it with others many times. There are various parts to the answer.
First and foremost - yes, a single action revolver can be used for self defense. They were used for 100 years, with top notch results, so there is no reason to gainsay them now. That's the easy reply.
Second - owning a single action revolver and shooting it occasionally is one thing; practicing with it is another. Are you mentally and physically qualified to use a single action revolver for self defense? In other words, can you cock it and fire it and cock it and fire it again? Will your hand(s) do the right thing and does your head know how to use such a weapon? If your answer is yes then we can move along to the next part of the discussion. But if you're going to pull that trigger and forget to cock the hammer you're not qualified, yet, to use that gun. And you still have to be accurate, too - don't forget that part. So be sure you practice and are "good" with it. Cowboy action shooters are good with them; that's what we do - but are you?
Third - Those items out of the way, let's talk about a "good shooting". If you use any gun for self defense you'll have to convince the police and prosecutors you had cause to defend your life - because you were in fear of death or severe bodily injury to yourself or a third party. If that's all true THE GUN DOES NOT MATTER.
You won't be faced with "
what are you, a cowboy?!" type of questions if the shooting is justified. It's the possibility of any issue with respect to the shooting that COULD, I won't say would or will, but
could cause some concern to a civil or criminal prosecutor. But in reality, neither your guns nor your ammunition will matter much in a justifiable homicide.
Interestingly, back in the day when I debated this with a whole host of gun and LEO experts, someone asked if ANYONE could find a case where these types of issues arose. None of us could.
I have several single action revolvers - maybe I'll use one for a CHL qualification someday, just to be able to claim that I KNOW they can be used for self defense because I qualified with one. We'll see.