What is the difference (if any) between "Striker Fired" and "Double Action Only" (DAO) - especially pertaining to the small, compact, semi-autos designed for CC.

My assumption has been that DAO in a semi-auto was the same as is a revolver - fairly long stiff trigger pull which gives the safety factor against accidental discharge. I shot a compact 9mm today (don't remember model but was not a Glock) that was described as striker fired and had no external safety. The trigger pull did not feel as "deliberate" as I would expect in DAO. It was light enough that I might not be personally comfortable carrying it.

I guess this conversation will probably move to the "Safe Action" of the Glocks too so i might as well bring it up.... Again I am not comfortable with using a Glock for CC.

Any info/explanation greatly appreciated.

I'm pretty sure that striker fired is similar to single action, only there is no way to decock it manually. Cycling the slide feeds a round into the chamber and cocks the striker, making it ready to fire.

At least that's my understanding after I did some research last year for a presentation on handling firearms.

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Can open, worms everywhere.

Let me toss this in and see if it stands up to discussion and debate.

DAO means that the pull of the trigger both "cocks" the firearm and then "releases" the hammer or the striker to fire the cartridge. As opposed to SA where there's a manually retractable hammer and the trigger just releases it, or DA (actually DA/SA) where the first shot is fired by pulling the trigger DA, but the second shot - or even the first, if the hammer is manually cocked - is all SA.

Most (all, maybe?) striker fired guns have the striker pulled back by the action of the trigger, meaning that (I'd argue) "all striker fired guns are DAO, but not all DAO guns are striker fired, since some have, for whatever reasons, hammers rather than strikers."

Glock can argue all they want about "Safe Action," but it's still a striker fired DAO pistol, I would say.

Amount of poundage to pull the trigger (yeah, yeah, I know that New Guys call it "press" but I'm Old. Deal with it.) is not terribly relevant to whether the system is striker or hammer/DAO.

Debate this amongst yerselves further.

The Glock has a 5.5 lb trigger pull. It can be fitted with a 10 lb trigger, the so called NY trigger. I have no qualms carrying a Glock with stock trigger.

For the Glock to fire the trigger safety has to be depressed through the complete trigger pull. The operation most likely to cause an AD is catching the trigger on a badly designed holster. Assuming the operator keeps his finger off the trigger unless the gun is pointed at something the operator intend to shoot.

3.5 lb triggers are available but those are meant for target or range use only.

Mr. Gunhobbit, I'd call the Glock a single action pistol. You can't cock it without pulling the slide back.

Then you can forget about the M&Ps which work essentially the same way.
Welcome to the 21st century and the striker fired guns, which strictly speaking are neither DAO nor single action: they are striker fired, with their trigger safeties and striker blocks.
Might as well ague whether your 2014 Ford is a "cart" or a "carriage." About as relevant.

All the action games lump striker fired into the "stock" DAO divisions for competition, regardless of the details of their interior workings. At one time, IDPA put the XD in single action and the Glock in double; now all the "plastic fantastics" are classified the same for IDPA and USPSA.

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Science plus Art

As the trigger is pulled on a DAO, the hammer is cocked and then released. The hammer strikes the firing pin, thus firing the gun. DAO, DA and SA pistols all have hammers and firing pins.

Striker fired guns do not have a hammer or a firing pin. As the trigger is pulled the striker is drawn reward and eventually released. The end of the striker acts as a firing pin and strikes the primer, firing the gun.

Most striker fired guns lack a manual safety, although a few, like some variants of the M&P do. There is no need to fear carrying a Glock or other striker fired pistol. If you don't pull the trigger then gun won't fire, simple as that.


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XDMs have palm swell safeties were the gun will not fire unless the hand is fully engaged on the handle. I assume Glocks operate the same way.

It is probably not helpful to take a manufacturer's name for its firing mechanism and make it into a TYPE of action. Example of "named" actions are Glock (Safe-Action) and Sprigfield (USA or Ultra Safety Assurance).

Semi-auto pistols generally have two types of actions: (1) hammer fired and (2) striker fired. There are sub-categories within each type. The distinguishing factor is whether the firearm has a hammer or not.

Examples of hammer-fired mechanisms are the Colt 1911, Browning High Power, Walther P38, S&W 39, Beretta 92, HK USP, SIG Sauer P220, Ruger P89, and similar. Some of these are SA (single action) and some are TDA (traditional double action) and some are DAO (double action only). Single action must be cocked in order to fire the weapon. TDA can be fired by the trigger, and after the first shot, subsequent shots are single action, in the sense that the hammer is left cocked until being decocked. DAO pistols are fired by trigger action, and hammer is never left cocked, instead decocking itself automatically after each shot.

Examples of striker-fired pistols are SIG Sauer 320, HK VP9, S&W M&P, Glocks, Springfield XD, and similar. In this type of pistol, the trigger engages the firing pin (striker) directly through a linkage called a trigger bar rather than by engaging and releasing a hammer to fall against the firing pin, as in the hammer fired type.

Within each type of firing mechanism, there are different operating systems.

Examples of hammer fired actions commonly referred to as DAO would be those in which the hammer returns to a fully- or partially-lowered position after each shot without separate decocking by the shooter. Specific types are the Beretta 92D, HKs with the LEM trigger, SIG Sauers with the DAK trigger, S&W 5946, 4046, 1046, 4546, etc. Within this category are some models, such as the S&Ws, in which the hammer is returned to a partially cocked position after each shot, as opposed to going to a full resting position. The partially cocked position makes the trigger pull easier, but usually does not allow a second shot without re-cycling the slide. I say usually as the HK LEM type does allow a re-strike, although with a heavier trigger pull. Other types of DAO pistols return the hammer to a fully lowered position, allowing re-strike capability. This type typically has a heavier trigger pull than the partially cocked type.

There is a similar sub-category of striker fired pistol in which the striker is left, after each shot, in a partially retracted position in order to make the trigger pull lighter. Glocks, M&Ps and XDs fit this category. Of those three, Glock's striker must be retracted further than those of the M&P and XD in order to be released to fly forward to fire a cartridge. Another sub-category of striker-fired pistol releases all striker energy returning the striker to a fully at rest position so that it is not under spring tension.

The bottom line is that NONE of these designs "go off" by themselves. I would venture a guess that more than half of all LE officers carry either a Glock or an M&P, including plain clothes officers carrying concealed. They simply don't "go off" without pulling the trigger. Are there negligent discharges? Yes, with any type. That, however, should not lead to a wholesale rejection of an otherwise fine and safe design.

On the other hand, if hundreds of thousands of officers carrying this type of pistol does not convince you of the inherent safety of the striker-fired design, or if you do not trust yourself enough to keep your finger and anything else away from the trigger by using a proper holster to cover the trigger, then by all means, carry what makes you comfortable. Or, don't carry at all.

Firearms are dangerous, and exactly NONE of them are proof against negligent handling. Thus, if a condition one (cocked and locked) single action 1911 frightens you, then use something else. If a partially (Glock) or fully (M&P and XD) cocked striker is not to your liking, then use something else. Some people are completely ok with no external safety on a revolver, but not with a pistol. Often, it is simply a misunderstanding of exactly how the firearm works and the fact that the inner workings are hidden from view more than with the visible hammer of a revolver or certain pistols. So, I always tell people that if their nerves will not allow the constant worry of carrying one type of action or another, then they should get a type with which they are comfortable.

A lot of modern striker fired pistols get designated DAO when most are really not. DAO means the hammer or striker is at rest until the trigger is pulled like a revolver. There have been striker fired pistols that we're true DAO such as the CZ-100, Walther P99DAO, Beretta 92D to name a few. I think the S&W Bodyguard is true DAO as well and I think H&K still offers the option of ordering their pistols with a DAO trigger. If a semi-auto is a true DAO, it will have 2nd strike capability(actually as many times you want to pull the trigger)and during dry firing, the trigger would cock & release the striker without having to pull back the slide whereas in something like a Glock whose striker operates from a half/partially cocked, during dry-firing, you have to pull back the slide every time you pull the trigger.

Did not mean to appear to pass judgement on any particular action type - just trying to learn. I fully understand that any unintended discharge is 100% on the shooter and controlling the weapon properly.

I am also a big believer in carrying what you know best and are most comfortable with. For me this is the DA/SA - Chiefs Special 9mm and Walther PPK. I carry in the DA mode with safety in fire position. This is the action I felt most comfortable with when I first started carrying, which was before the compact CC DAO pistols became readily available. I also like the SA follow up shots.

However, since my original post, I have fired some of the DOA 9mm (sig) and really liked them. The trigger pull is smoother than the DA on my CS9 but still deliberate enough to make ME feel comfortable carrying it. Had these little gems been available when I got started I probably would have never found the CS9 - which would have been a travesty.......

Thanks for all the info