For all of you gun pros, don't turn up your nose and think "stupid" yet. In my 10 years of being in the gun business, I've discovered that many pretty experienced gun people don't really know the difference between single action, double action, or single/double action handguns.
In the old west days of revolvers it was pretty simple... you had to cock the hammer each time before the revolver would fire. Then came the semi-auto handgun with a hammer. Most noted in the beginning was the Colt 1911, which also had to have the hammer cocked each time before it would fire. Of course the 1911 cocked itself with the slide action every time it fired... so it was a semi-auto single action pistol.
Okay... double action and single action actually came from the revolvers so we'll use them as an example. A revolver that fires every time you pull the trigger is considered "Double Action". A revolver that requires the hammer to be cocked before firing is a "Single Action". A revolver that can be fired by simply pulling the trigger or by cocking the hammer and pulling the trigger is a "Single/Double" action revolver. So we have "Single Action", "Double Action", and "Single/Double" action revolvers. Then came the gangster's favorite, the "Double Action Only" revolver... no exposed hammer. The gangsters didn't like this revolver because the hammer didn't snag in their purse or pocket -- they liked it because they could shoot it from their coat pocket. Sure it cost them a coat or two because of the holes, but that's a small price to pay for their life.
Before we move to the semi-auto pistols of today, let's look at the "Single/Double" action revolver a little closer. Pull the trigger and it will fire -- cock the hammer pull the trigger and it will fire.. so it's single action and double action. But one thing to note: when you cock the hammer for single action shooting, the trigger is reset to a shorter trigger pull than when you are shooting the revolver in double action.
All the same classifications are true in today's semi-auto pistols -- yep... no difference -- but, in my opinion to the truest definition, many are not classified correctly. Let's take the Beretta 92 -- widely used by the military. A hammer fired Double/Single action pistol. It's exactly the same as a Double/Single action revolver... pull the trigger it fires, cock & pull, it fires -- and when cocked the trigger is reset for a shorter pull.
Then came the hammerless "striker fired" pistols to muddy the water. No hammer to cock. But we can cock the striker by pulling the slide back... so the slide must have taken the place of the hammer !
Go to our handguns and look up Glock, Springfield XD's, and Taurus -- under "Action", they all say "Double Action". I don't believe this !! Take your
NOT LOADED Glock or XD out - pull the slide back to cock the striker and then pull the trigger -- it fires -- now pull the trigger again. Does it fire the second time? -- NO. So how can it be double action? I understand all their engineering mumbo jumbo about having to pull the trigger to put tension on the striker pin... but let's keep it simple. It's the same as a 1911 in that it has to be cocked each time in order to fire -- so I think it's really "Single Action Only". Now try your later model Taurus -- you don't have to pull the slide back to cock the striker -- it will fire every time you pull the trigger. It must be "Double Action Only" ! The reason the Taurus is not "Single/Double" action is because it does not reset the trigger for a shorter pull when the slide is pulled back.
In the foggy distance of my memory, it seems there are a couple of striker fired pistols that are truly "Single/Double" action where they will fire anytime the trigger is pulled and the trigger is reset for a shorter pull when the slide is pulled and the striker cocked. Maybe it's Walther or Smith & Wesson... and then maybe they are internal hammer rather than striker fired?? -- not sure.
Did this change you life ? -- okay... probably not. Yea mine either, but it's something to think about on a cold wintry, rainy, snowy, day when you are caught up with all other things in the world.