Is "double action only" correct?


Alan Fud
May 6, 2003, 02:05 PM
A "single action" gun needs to be first manually cocked and assuming that there is a live round in the chamber, pulling the trigger will fire the gun -- thus the gun is capable of a 'single action'.

"Double Action" implies that the gun is capable of two actions when the trigger is pulled ... (1) cocking the hammer back; and (2) dropping the hammer down.

So far, so good.

"Double Action Only" implies that the gun is capable of two actions ... that of cocking the gun and firing it but does not have the ability to be pre-cocked and left in Single-Action mode.

Some guns fit this description ... certain DAO revolvers as well as some pistols from Beretta, SIG, etc. However, there are a lot of DAO pistols out there (Glock, Kahr, S&W, Para, etc.) that are called DAO but require the striker to first be pre-cocked partially otherwise all of the pulling in the world on the trigger will not fire the gun.

To me, this is no different from the "single action" capability of a 1911 which required the hammer to be manually cocked. These DAO guns from Glock, Kahr, S&W, Para, etc.; require the internal striker to munually pre-cocked.

More accurately, shouldn't these guns be classified as 'Single Action' or maybe even 'Single Action Only'? I don't understand how they can be called "DOUBLE Action Only'.

I'm not talking about the SIGs & Beretta's which have a repeat striker capability and which truely are DAO but I'm making reference to the Glocks, the Kahrs, the Para's, and the S&W's.

If you enjoyed reading about "Is "double action only" correct?" here in archive, you'll LOVE our community. Come join today for the full version!
May 6, 2003, 02:35 PM
Glocks may be CALLED DAO, but not by Glockself. They call them 'safe action pistols'. Kahr calls its pistols 'trigger cocking DAO, and though I don't know the internal operations well enough to tell, that seems more accurate to me; the trigger take-up is clearly doing more work in a Kahr than a Glock.

A true double action only pistol assigns the trigger both duties of cocking the hammer/striker and releasing the sear, with no optional holding position in the middle (unless it's your finger doing the holding). So my centennial revolver is DAO, definitively. Glock, not so much, since the striker is at least partially cocked by the slide's action. I think Kahr's is at least partially cocked, too. Dunno 'bout the rest.

4v50 Gary
May 6, 2003, 02:47 PM
DAO is pretty clear and you've got the concept.

Now, throw in the Glocks and now you've got a single action and a half. I hate the "safe-action" and it is probably more liability or marketing inspired than descriptive of the action. The trigger on the Glocks, as we all know, cannot be pressed for that failure to fire. You can do that with the Ruger P95 or P97, Beretta & Sig DAO or unmodified SA/DA revolvers. With Glocks and its cousins, it's immediate action drill (tap, rack, ready) when it don't go boom.

May 6, 2003, 04:51 PM
Well some would say if you really want to get into the sematics of it "DAO" is an incorrect term all together.

I think what they were really talking about originally was "Single action" one way to fire the weapon cock, then short light trigger pull.

"Double action" two (double) ways to fire the weapon long heavy or short light.

Looking at it that way DAO means.... :uhoh:

May 6, 2003, 04:57 PM
The term "Single Action" cannot be applied to Kahrs.

The trigger pull does two things: 1) draws the striker back, and 2) releases the striker. When the striker is released and goes all the way forward, it passes the cocking cam. If the gun does not fire, the striker remains out of the reach of the cocking cam.

The slide must cycle to bring the striker behind the cocking cam. With the striker resting on the cocking cam, there is very little spring pressure on it . The gun cannot be considered cocked. It is merely positioned so that it can be cocked with the next trigger pull.

(Note: The Kahr also has a "striker block releasing cam" mounted beside the cocking cam. When the slide cycles, the striker block springs into "blocking" position, and is released as part of the trigger stroke.)

May 6, 2003, 05:15 PM
SA: A trigger pull does only ONE thing to the striker or hammer; it releases it.

DA: A trigger pull does TWO things to the striker or hammer; it 1) cocks it and 2) releases it.

DA/SA: On the first shot (semi-auto), you have the option of manualy cocking the hammer, or having the trigger pull cock the hammer.

DAO: There is no option. The gun cannot be manualy cocked.

May 6, 2003, 09:16 PM
I'd go with hd1, otherwise nothing makes sense. Consider:

If a Sig is just "DA", wouldn't that imply that it should work like a "DA" revolver?

But a Sig is an auto, it cocks itself! Many autos do not, but some, like the Browning BDM, can still be manually cocked, like a revolver.

Then there is DAO. DA being your Only choice.

It has to be based on the function of the trigger, whether it performs two actions at once, or a single action at a time, or both (DA/SA).

If "DA" is simply the ability to trigger cock or manually cock, how does one explain the P99, that can't be manually cocked, but cocks itself on cycling?

As far as Glock, USP LEM, Fast Action, P99 QA and others go, these are hybrid DAO/SA systems. In all these cases, a second spring is employed, making the mainspring neither cocked nor relaxed, but in a limbo between.

Perhaps "assisted DAO" would be appropriate.

May 6, 2003, 10:21 PM
"Double action" two (double) ways to fire the weapon long heavy or short light.It was my understanding that this is what "Double action" originally meant, but that the term has been redefined over the years to its currently accepted meaning.

There's only one way to shoot a Glock. To me that means it has only one action (single action.) But it's Gaston's gun. He can define it anyway he wants. The Glock is a safe-action gun :D

May 6, 2003, 10:41 PM
But it's Gaston's gun. He can define it anyway he wants. The Glock is a safe-action gun
Unless the contract specifications say DAO then it becomes DAO just as quick as the salesman's lips can move!

May 7, 2003, 05:28 PM
I have always understood it from the same perspective as hd1

May 7, 2003, 07:47 PM
Don't sweat it Alan, its all semantics.

Alan Fud
May 7, 2003, 08:05 PM
Mannlicher, I bring this up because with current terms, there is no way to tell if a gun has a repeat striker capability. Both my Kahr MK9 and NAA Guardian are classified as DAO. If I experience a light striker hit with the NAA, I can pull the trigger a second time and there is a good chance that the second hit will set off the round -- an important feature if you find yourself in a sruggle or some other situation where your second hand is not free to rack the slide and chamber another round.

If the same thing happens with my MK9, I can pull the trigger all day long and nothing will happen because it lacks a second striker capability.

It would be nice if the same term (DAO) meant the same thing. A S&W DAO auto does not have a repeat striker capability but a S&W DAO revolver does. A Para DAO pistol does not have a repeat striker capability but a Beretta DAO pistol does. Etc.

May 7, 2003, 08:29 PM
I have alway felt "DAO with a second strike capability" for weapons like your Guardian, and "DAO without a second strike capability" for weapons like the Glock would be better descriptions. It recognizes that pulling the trigger is accomplishing the double action of compressing the mainspring (or the striker spring) and firing the weapon, but also provides a better description of the limitation of those weapons without a second strike capability.

May 8, 2003, 02:04 AM
someone explain how you can have half an action and I will stop calling glocks DAO.

May 8, 2003, 07:36 PM
Who here can tell to whom or what the word "Action" in SA/DA/DAO is referring to - the shooter's action or the gun's mainspring compression?:scrutiny:

I have to believe it's intended to represent the shooter's perspective, not the motion of the gun's part/s.

If 1911's are traditionally classified as SA, then Glocks, Kahrs, & LDA's should only be considered single action only, IMO. These guns don't have a restrike capability, and are even disadvantaged as these also don't have a visible striker/hammer that can be cocked manually to 'prime' them to fire.

Not to flame anyone, but 1911's are better than Glocks in this regard as they have a manual restrike capability; they should be classified SA with manual restrike.

DA's are just that, cocking and firing could be done with one trigger stroke, while I'd classify the Kel-tec's, Millenium pistols as true DAO's.

May 8, 2003, 07:46 PM
Is "double action only" correct?

Yes and no.:rolleyes:

May 8, 2003, 08:22 PM
A double action, either revolver or auto, has two fire control options, in that the operator may select to either fire the piece by trigger action alone, or he may cock the hammer and fire it by pulling the trigger. This definition has applied since the first cap & ball double-action revolvers were offered in the mid-to-late 1800's.

A weapon with only one fire control option cannot be a "double-action", anymore than a unicycle can be a "bicycle". I am aware that we now have all these new autos that exist in "quarter cock", or whatever you prefer to call it, and that the pulling of the trigger lever finishes the cocking and firing process. Whether it fires from dead-rest or quarter-cocked, one fire-control option equals a single-action. It may be a trigger-actuated single-action, but it is a single-action nontheless.

Of course we don't exist in the 1800s anymore, and new designs have become prolific and quite popular. Selling them with 1800s nomenclature does not work. So, the new designs have been given various names, mostly according to marketing concerns. Single-action had become something of a dirty word among law enforcement administrators at the time these names were selected. I note with some humor the chameleon-like talents of at least one, which seems to become a "double-action" on demand- and depending upon bid specifications. It matters not. The marketers of these guns would do well to make up a name for them, and stick to it.

The introduction of new firearm types does not change the terminology or design of existing ones. They simply need new and accurate names. We can surely accomplish this without calling bolt-actions "lever-actions", or anvils "can openers".

May 8, 2003, 08:51 PM
The marketers of these guns would do well to make up a name for them, and stick to it. See? The Glock is a "safe-action" gun. :D

May 12, 2003, 07:07 PM
The Kahr series of pistols is actually closer to the Glock, because the Kahr's striker spring is partially compressed even before the trigger and cocking cam are brought backwards by the user. How does it get partially compressed? By the slide's movement. Not really a big deal, but it helps maintain a shorter trigger stroke than it would have without the pre-compression. Dunno about what it does to the designation of DAO... :) (As I'm sitting here with my K9 torn apart!)

Ala Dan
May 12, 2003, 11:52 PM
Most of you folk's know me pretty well by now; and
with that said, you also know that I tend to favor
self-loader's of the DA/SA design much of the time.
DAO is OUT for me, as I like exposed hammers on
all of my semi-auto's. That is the only complaint I
have against Glock's striker-fired firearm's. I very
rarely cock the hammer on my SIG's for the first
shot; but its there if I ever decide to use it!:rolleyes:

Best Wishes,
Ala Dan, N.R.A. Life Member

Shawn Dodson
May 13, 2003, 01:51 PM
someone explain how you can have half an action and I will stop calling glocks DAO. I consider Glocks DAO. You press the trigger and it: 1) cocks the striker, and 2) releases the striker. Trigger reset is just that.

As for the term "DA/SA," I believe it is dumbed down, redundant terminology for "DA."

May 13, 2003, 01:56 PM
You can have half an action when you have an extra spring helping you pull the trigger. Is it truly "double action" if you're only doing half the work?

Shawn, would you then say a DA revolver and DA Sig are the same thing?

May 13, 2003, 05:34 PM
So long as pulling the trigger performs the DOUBLE action of: FIRST compressing the mainspring (or striker spring) thereby storing enough energy to ignite the primer, and SECOND releasing that stored energy to strike (ignite) the primer, it is by definition DOUBLE action. The fact that the action may (or may not) be "set" has nothing to do with the DOUBLE action of the trigger. Try not to confuse the "feel" of the action with mechanics of action.

May 13, 2003, 05:52 PM
I'm not confusing feel and mechanics. A glock has both a helper spring AND starts partially cocked.

If that isn't important, consider the CZ-75. When 'cocked' in SA mode, the trigger bars push the hammer back several degrees to release the sear. So that meets your definition of double action; the mainspring is compressed (a bit) and released.

So a Glock is 30% cocked, a Steyr M is 60% percent cocked, a USP LEM has two mainsprings, one fully cocked (50%), an XD 90% cocked and a CZ-75SA and clones are 95% cocked.

By your limited definition, these are all DA pistols.

Not a useful definition.

May 13, 2003, 08:01 PM
No, Handy, you are muddying (deliberately?) the issue. Go back and look at "my definition." "FIRST compressing the mainspring (or striker spring) thereby storing enough energy to ignite the primer.''

The CZ when "cocked" mode has enough energy already stored in the mainspring to discharge the firearm. The fact that pulling the trigger has to move the hammer back slightly to release the sear is moot--the mainspring is not being compressed in order to fire the weapon but only to release the sear. In other words, it is only performing the second (single) action of "releasing that stored energy to strike (ignite) the primer."

The Glock does not have enough stored in the striker spring to ignite the primer so pulling the trigger performs the
DOUBLE action of: FIRST "loading" the striker spring, and SECOND releasing the striker spring to ignite the primer--a classic DOUBLE action.

I am not familiar enough with the Steyr or the USP LEM actions to discuss them, but if the striker spring (or springs) have already stored enough energy to ignite the primer, all pulling the trigger does is release that energy then the trigger is only performing a single action. The XD-series and CZ75SA are already cock--the fact that in releasing sear the mainspring is very slightly compressed is mute. For all practical purposes, in terms of the actions required to fire a pistol, all pulling the trigger does is released the energy already stored in he main/striker spring.

It's really easy unless you try to confuse it: if pulling the trigger is required to compress the main or striker spring in order to store sufficient energy to ignite the primer, the it is double action. It is definitely not rocket sciene.

May 13, 2003, 08:06 PM
Okay, you win.

Now, what good does labeling everything "DA" do for you? It's not an important mechanical definition, since the inside of a DA Glock and SA Steyr are nearly identical. It also isn't instructive for operation or trigger style.

So what are we to do with this useful term?

May 13, 2003, 08:42 PM

Oh yeah, forgot an important question.

Since you are defining "cocked" by the compression of the mainspring, what do you do with weapons that have a cocked mainspring and a relaxed hammer or striker? The mainspring is cocked, but has no energy to deliver since the hammer is down.

I'm not making this up. It's how the FN designed Fast Fire trigger in the Daewoo works. The hammer is at rest, the mainspring cocked, and the trigger set to a long, light "DA" pull. Once the hammer comes full back the mainspring and hammer are released together.

By you're definition, this gun is SA.

May 14, 2003, 01:00 AM
There was a time when these terms meant something, but these days there are a lot of guns that are neither fish nor fowl.

I was talking with a friend and my gunsmith at the shop once, and we were discussing DA autopistol triggers (specifically I was opining that the DAO Beretta may have the sweetest) when this guy walks up and says "What about the Para LDA? It's a lot lighter." We all just kinda looked at him for a second, and tried to point out that we meant "true double action", so comparing a Beretta that trigger-cocks the mainspring with an LDA that cocks it with the slide just like a regular 1911 is kinda apples and oranges.

Well, actually, triggers were once just apples and oranges, now there're bananas and pomegranates, and peaches and...

So I've officially given up. I'm finally comfortable with describing some newer trigger mechanisms as "sorta DA" or "pretty much Single Action-like" and not losing any sleep over it. ;)

Shawn Dodson
May 14, 2003, 07:45 AM
Shawn, would you then say a DA revolver and DA Sig are the same thing? Hmmm..., let's see...

DA Revolver

DA Automatic

Seems to me the term "DA" accurately describes both.

If you enjoyed reading about "Is "double action only" correct?" here in archive, you'll LOVE our community. Come join today for the full version!