definition of single action / double action

[longhornmike]

i get a little confused when the definition of single action / double action is discussed for either revolvers or pistols.

are there any simple illustrations or explanations that could help?

thanks

[seamusTX]

It's simple:

In a double-action firearm, pulling the trigger raises the hammer from the decocked position and then releases the hammer to discharge the weapon.

In a single action, pulling the trigger drops the hammer only from the cocked position. The hammer must be cocked manually or, in the case of semi-automatic pistols, by the rearward movement of the slide.

This article is accurate: http://en.wikipedia.org/wiki/Trigger_(firearms" onclick="window.open(this.href);return false;)

- Jim

[Purplehood]

It's simple:

In a double-action firearm, pulling the trigger raises the hammer from the decocked position and then releases the hammer to discharge the weapon.

In a single action, pulling the trigger drops the hammer only from the cocked position. The hammer must be cocked manually or, in the case of semi-automatic pistols, by the rearward movement of the slide.

This article is accurate: http://en.wikipedia.org/wiki/Trigger_(firearms" onclick="window.open(this.href);return false;)

- Jim

I too am a novice at this. How does all that apply to handguns like mine that have no hammer (external)? That would make them single-action by default, correct, or is that what makes them semi-automatic?

[CainA]

I'll give it a shot(no pun intended):

SA Only=vintage revolvers(like in western movies) and 1911 style semi-auto pistols as said, hammer must be cocked to fire.(Ruger blackhawk and similar and colt and copies of semi-auto flavor)

DA/SA=Semi-auto pistols, hammer can be in the uncocked down position; pull trigger, hammer goes cocked and falls, this is the same as with DA revlolvers, but here's where it all changes, typically in a semi-auto, after that first double action shot, the slide moves back to put it in SA mode(hammer cocked back) all subsequent shots are single action, unless there is a hammer fall safety, which drops the hammer, which in turns returns it to double action(example: S&W 3913 semi-auto and similar guns)

SA/DA-I think this is kinda new, strange to me, single action similar to above, however, if the round in the chamber fails to fire after you pull the trigger, you just pull the trigger again and see if it fires the 2nd time around, or 3rd or 4th...etc. if/when it does fire, you're back to single action similar to above.(example: 3rd generation Taurus PT Pro series)

DA Only- is well, you can only fire it in double action, you cannot 'cock' the hammer to put it into single action mode.(1st and 2nd gen. Taurus PT111)

Just a side note, a lot of revolvers are DA, although of course you can fire them in SA mode if you like by manually cocking the hammer back, but I guess you figured as much. SA revolvers are SA Only, you MUST cock the hammer to fire them.

I tried.

-Cain

[seamusTX]

How does all that apply to handguns like mine that have no hammer (external)?

Some double-action revolvers and pistols have a shrouded hammer, but they work the same as a regular double-action. The Kel-Tec P3AT would be an example of that.

Pistols like Glock don't have a hammer. The part that strikes the firing pin to ignite the primer is a called a striker. However, they function like a double-action. You don't have to (can't, actually) cock them manually.

People have been arguing forever about whether certain pieces are "really" double- or single-action.

You can find some excellent animated videos of the workings of a Glock and several other firearms online. I'm too lazy to search for them.

- Jim

[longhornmike]

yep , some of those arguments are why i got confused. you guys have helped.

i have a springfield armory xd.45 acp pistol and a taurus millineum pro 9mm , i consider both single action.

would that be correct ?

[CainA]

If the Taurus is the 3rd generation, then yes it's SA/DA. If it's generation 1 or 2 then it's DAO. I'm not familiar with the XD so someone else will have to answer that.

-Cain

[kd5zex]

The Springfield XD is a striker fired single action. It will not fire until it has been cocked by cycling the slide.

[Cosmo 9]

I'll add to the confusion a little more. I've always considered "striker Fired" to be half cocked (like myself) and pulling the trigger moves the striker even farther back and then releases it. The trigger can't move the striker from the uncocked posistion. I've always put them in between SA and DA.

[CompVest]

I just think of it as:

single action - does one thing - drops hammer
double action - does two things - cocks and drops hammer
safe action - releases striker

[longhornmike]

well now i see that it really is confusing , and in some cases , just semantics.

thanks for the tips.

[stroo]

Just to confuse it further some striker fired pistols like the Glock are more like SA because you need to work the slide, ie cock the gun, to fire it while others like the Kel tecs are more like DA because pulling the trigger actually cocks the striker.

[Mike from Texas]

Just to confuse it further some striker fired pistols like the Glock are more like SA because you need to work the slide, ie cock the gun, to fire it while others like the Kel tecs are more like DA because pulling the trigger actually cocks the striker.

That's not entirely correct on the Glock. The difference between the action of the Glock and an XD is that the Glock's striker assembly is under little to no tension at rest. When the trigger is pressed, the trigger bar actually grabs the striker and moves it rearward against the striker spring while at the same time releasing the drop safety. As it comes to the rear of the cycle of the trigger the connector releases the trigger bar and the striker falls forward. On the XD, when the slide is cycled, it does actually load and cock the striker assembly so it is in essence a single action at that point. That is why the Glock trigger feels a little heavier than the XD trigger. The Glock is in essence cocking the striker when the trigger is pulled whereas the XD is not.

[Skiprr]

That's not entirely correct on the Glock. The difference between the action of the Glock and an XD is that the Glock's striker assembly is under little to no tension at rest.

Very good description. I hope it doesn't strike (pun intended) fear into those folks trying to understand SA versus DA in an age where the mechanisms have distinctly blurred. But your description is precisely why, if shooting IDPA, a Glock is allowed in the Stock Service Pistol division, but a comparable XD isn't.

John Farnam's thought on the matter is: "The two terms, double- and single-action, are so muddled that they have now become inexplicit and virtually useless for the purpose of any accurate description of an autoloading handgun operating system. The terms are still useful only in differentiating revolver types."

[longhornmike]

now i don't feel do dumb , thanks.