Ok, in a recent trip to Bass Pro, I was looking for some double action only or DA/SA guns and one of the guys at the counter mentioned an XD which I own already as double action, now to my consideration, I don't think of a striker fired pistol as DA, what says you? And why?
Depends on how you define it. I adhere to the original intent of double action as defined by Dr. Ezell.
Double action originally meant the pistol is able to be fired two ways (thumb-cock and trigger-cock). If you cannot fire a pistol two ways, it is single action.
However, I understand that I am in the minority opinion . . . plus I am hardly an authority on firearms (unless you count breaking them).
I also have an XD and to my understanding - the striker is fully cocked on its own - as opposed to the Glock type action where the striker is "Mostly" cocked, and the trigger completes the cocking of the striker - so the XD really is Single Action.
“When I use a word,” Humpty Dumpty said, in a rather a scornful tone, “it means just what I choose it to mean—neither more nor less.”
So, single-action, double-action, and double-action/single-action can mean whatever one wants them to mean.
Here's my take, as they apply to modern semi-automatic pistols:
Single action means the trigger performs only one function: releasing a cocked hammer. The most well-known examples are 1911-type pistols.
Double action refers to those pistols with somewhat longer trigger pulls that both "cock" and release the firing mechanisms. The length and force of the trigger pull stays the same for all shots. Glock is the most well-known of such types.
Double-action/single-action (DA/SA) refers to pistols, typically with external hammers, that can be fired "double-action" from the hammer down position, and subsequent shots "single-action" with the hammer cocked by the action of the slide from the previous shot. The length and force of the trigger pull changes, depending on "single" or "double" action. The Berretta M9 is a good example of such pistols.
Of course, there are differing opinions on SA, DA, DA/SA, but the above seems to be common.
The fact that a pistol is striker fired doesn't determine the action type. XD's are a true single action as the trigger only performs one action to fire the gun. Pistols such as glock and SW M&P are double actions because the trigger performs two actions to fire the gun.