The following information on single action vs double action shooting comes from Section 33 of Shooting by J. Henry FitzGerald. Shooting is also available to purchase in print.
Single action vs double action shooting? This has been the controversy among the shooters. Let us first take the claims of the single-action converts. They claim that more accuracy can be attained in this way. Now we are speaking of police work and not target shooting and we must all agree that if an officer must fire a shot in self-defense the bullet has no effect until it strikes his opponent. An officer’s life is in very little danger except at short range (by short range I mean inside of fifteen feet) and at this distance extreme accuracy is not as important as speed. The question has been asked me many times: “Why do you instruct the police to practice double-action shooting?” My answer to this is: “Because in fast shooting every officer will shoot double action.” Imagine yourself with a double-action revolver in your hand at short range, knowing that your life depended upon your speed, cocking your revolver for each shot. Double action is one motion as you draw your revolver and point it, pull the trigger and your first bullet is on its way. Single action, draw the revolver, find the low hammer used on all double-action revolvers, draw it to the rearward position until it locks, with the chance of your thumb slipping off the hammer as you cock it, especially in cold weather.
The double action was placed in revolvers to use and as an improvement over the old single action. While single action is correct for slow fire and long range shooting it is incorrect where speed is desired. Ninety per cent of effective police shooting is inside of ten feet and less than two seconds to get into action. Any one who will practice double-action shooting will be surprised at the accuracy. Target men will shake their heads and tell you it can’t be done. It is done, and I can name officers who use this double action in matches where plenty of time is allowed for single-action shooting, and they are making good scores.
The way you practice is the way you will shoot when you are protecting your life; if you have always practiced slow, deliberate fire you will know no other way.
And now I know I am going to hear from the lovers of the “Old Peace Maker,” the single-action army, “How about us?” The single action is a wonderful arm; always the favorite of the old-timers and in a class by itself. For the man who has lived with the single action and who has practiced with it until he has mastered the art of quick draw and getting the first shot away it is a wonderful arm; but for the officer of today who has never taken the time to become familiar with any revolver he will find that he can master the later double-action revolvers in less time then he can the single action, which would in most cases be too heavy for his work.
The double action has its advantages for many occasions where the officer must carry his revolver ready for instant use, as in entering a house or room in which he has every reason to believe a criminal is hiding. If he should enter the house with his revolver cocked, a loud noise, as the slamming of a door or the throwing of some article, may cause him to fire a shot because less than one-eighth of an inch pull will release the hammer. On the other hand, if the revolver is carried with the finger near the trigger ready for double-action shooting five-eighths of an inch is required to fire the shot and for a quick shot it is not necessary to have the finger on the trigger, but just outside ready to slip inside the guard.
I have heard many senseless arguments why double actions should not be used. I remember the Pennsylvania State Police Team coming to Camp Perry and shooting double action in the matches. The old target men said it couldn’t be done, but they did it and did it well at twenty-five yards. I do not recommend double action in this work, but I do recommend it for police shooting at close range. One reason that single action and target shooting was taught to police departments in years past is the fact that some one in that town or city, known as a good shot, either offered his services or was asked to instruct the officers. If he had never practiced in any way except at a target at regulation distance he would, of course, teach target shooting.
Target shooting or any other kind of revolver shooting will help the officer, but what he must eventually have is rough and tumble shooting, using speed rather than extreme accuracy. The idea is submitted through the motion pictures and western stories that no arms are used in the West except the single action. This is not true, and thousands of .38 and .45 caliber double-action revolvers and .38 and .45 caliber automatic pistols are used.
Many advance the idea that the single action is more dependable than the double-action revolvers; that if they were to locate in some out-of-the-way place or explore darkest Africa where a repair shop could not be reached for six months they would take the single action. I do not agree with this; the modern double-action revolvers will fire more shots and still remain in working order longer than the single action. I know I will hear from this statement but, nevertheless, it is true. Don’t get discouraged, single-action men; you still have your pets and this statement will only make you love them more than ever.