[ugaarguy]

In the past quarter century semi-automatic handgun design and development has exploded. There are so many trigger mechanisms out there that it's confusing to even experienced handgunners. In this thread I'll try to cover the types, names, basic operation, and major examples of each.

The Basics
We'll start with the three primary trigger mechanisms and build from there.

SA - Single Action. In this mechanism the firearm's hammer is fully cocked, and the trigger pull performs the single action of dropping the hammer to hit the firing pin and fire the round. These pistols are generally carried "cocked & locked", where the hammer is back and safety is engaged. Well known examples of this are the M1911, Browning/FN Hi-Power, some variants of the HK USP, SIG P-Series SAO pistols, CZ-75 SA, and FN FNP SA.

DA - Double Action. In this mechanism the trigger pull performs the two actions of cocking the hammer, and then releasing it to fire the round. The British often refer to DA as "Trigger Cocking" for this reason, and it helps many folks to think of DA in this way. DA autos are further split into three other categories as follows.
DA/SA - Double Action / Single Action. These pistols fire the first round Double Action, and all following shots are fired single action. They generally use a decocking lever to safely lower the hammer, but block contact with the firing pin so the chambered round is not fired.
Caution Decockers can fail, so always point the pistol in a safe direction when decocking. Decocker failures are rare in modern firearms, but do occasionally happen. Some older designs are more prone to failure. If you have any doubt that a decocker is not working properly have the firearm checked by a competent gunsmith or armorer.
DAO - Double Action Only. In these pistols the hammer always stays down, and the trigger operates only in Double Action.
Many well known brands of pistols are available in the Double Actions. Some are only available DA/SA or DAO, and many are available in either mechanism. Well known examples include SIG, H&K, CZs and Clones, Ruger, Taurus, Kel-Tec, Walther, FN, Beretta, and Smith & Wesson metal frame autos.
DAO with reduced trigger pull - These are the new breed of DA pistols, pioneered by Para Ordnace's "LDA" - Light Double Action. These pistols keep the hammer down, but cycling the slide pre-tentions the main spring / hammer spring. The result is a lighter weight DAO trigger pull, and some also provide for a shorter trigger pull & reset. Some also have the ability to revert back to a full weight DA trigger pull to give a second try if the round does not initially fire - this is known as restrike capability. Beyond Para's LDA, examples are SIG's DAK, H&K's LEM, and some Kel-Tec and Smith & Wesson Pistols. Edit: It has been brought to my attention that the hammer rests in a partially cocked position on the Kel-Tec PF-9, P-32, and P3AT; and possibly a few other pistols as well

SFA - Striker Fired Action. These pistols use a Striker, basically a hammer & firing pin in one. Most operate similarly to a lightened Double Action. Cycling the slide partially pre-cocks the striker, and the trigger pull finishes cocking the striker before releasing it to fire the round. Some pistols have the striker pre cocked only a small to moderate amount and are much like DAO in a traditional hammer & firing pin pistol. Others almost fully pre-cock the striker and are much like SA in a hammer & firing pin pistol. Others yet have striker mechanisms that are much like DA/SA. Glocks are undoubtedly the best known SFA pistols; others include Springfield Armory XD, Walther P-99 / S&W99, S&W M&P and Sigma, Taurus Millenium, Mil. Pro, 24/7, and CZ 100.

No doubt I've left some things out. If I've left any glaring omissions, or made any major or minor errors, please send me a PM and I'll edit to correct them.

If you'd like to add anything please feel free to post a follow up. If you could, please also stick with the definitions of trigger/operating mechanisms I listed above to keep things simple and avoid confusion. In your follow ups please stick to objective information and avoid being subjective. We can debate our preferences & the merits of the various mechanisms in another thread, but please keep this focused as an informative reference.

Thank You.

Edit 17 Jan 07: I corrected the first glaring omission I noticed and added Beretta to the major examples of DA pistols along with a couple of other tweaks

[marzen]

Great write up and thanks for sharing!

[PX4MAN]

Thanks Ugaarguy, I'm going to print
this out and make some copies to just
hand out when somebody wants an
explanation and be correct and cover all.

john:)

[ugaarguy]

THR member Fastbolt recently made a great post in another thread about SIG's DAK. He tells me that the info is basically what's in the SIG armorer's manual with a little of his own commentary added in. The post also offers his thoughts on traditional DA/SA vs. the new modified DA systems from an experienced perspective. Good info; http://www.thehighroad.org/showthread.php?t=242758

[rcellis]

Where does the Walther AS and QA triggers fit in? And the 'New York Police' trigger?

[ugaarguy]

Where does the Walther AS and QA triggers fit in?
The QA - Quick Action - is a light DA version of SFA, much like the system Glock uses. The AS - Anti-Stress - is a SFA that replicates the feel of a hammer & firing pin DA/SA with a long pull first shot, and short pull on subsequent shots.
And the 'New York Police' trigger?
The "New York" trigger on Glocks is a modification that increases the trigger pull weight. The various weights of Glock trigger are provided by connectors or varying geometry and/or connector springs of varying weights. As far as I know trigger pull length and reset remain the same. The folks over at www.glocktalk.com can give you more detailed information on the many Glock OEM and aftermarket trigger modifications that are currently available.

Please let me know if I can be of further assistance. If anyone has more detailed or accurate information please feel free to post it.

[briansp82593]

dont forget lda also it must be cocked but when its cocked it protrudes only a few mm's so im thinking that would classify as sa? or i dont know :(

[PaladinX13]

For "Errata" you probably could make some mention of the new Taurus SA/DA trigger mechanism (I know it's confusing since Taurus recycles model names). And I'm not sure it really falls into the arena of triggers, but maybe a mention of things like the SFS Browning Hi-Power hammer?

[CJ]

For "Errata" you probably could make some mention of the new Taurus SA/DA trigger mechanism (I know it's confusing since Taurus recycles model names). And I'm not sure it really falls into the arena of triggers, but maybe a mention of things like the SFS Browning Hi-Power hammer?

Agree with PaladinX13.

SA/DA - Single Action/Double Action. Currently in use on some Taurus models. These pistols are designed to fire the all rounds Single Action. If there is a failure to fire, these pistols have the capability to fire in Double Action mode (referred to as second strike capability: allowing a second strike on a primer, frequently firing it on the second attempt).

[Soybomb]

DA/SA also goes by its older name of traditional double action, or TDA alot.

[default]

Overall, an excellent summation and on a subject I find very interesting. However -

DAO with reduced trigger pull - These are the new breed of DA pistols, pioneered by Para Ordnace's "LDA" - Light Double Action. These pistols keep the hammer down, but cycling the slide pre-tentions the main spring / hammer spring. The result is a lighter weight DAO trigger pull, and some also provide for a shorter trigger pull & reset. Some also have the ability to revert back to a full weight DA trigger pull to give a second try if the round does not initially fire - this is known as restrike capability. Beyond Para's LDA, examples are SIG's DAK, H&K's LEM, and some Kel-Tec and Smith & Wesson Pistols. Edit: It has been brought to my attention that the hammer rests in a partially cocked position on the Kel-Tec PF-9, P-32, and P3AT; and possibly a few other pistols as well

SFA - Striker Fired Action. These pistols use a Striker, basically a hammer & firing pin in one. Most operate similarly to a lightened Double Action. Cycling the slide partially pre-cocks the striker, and the trigger pull finishes cocking the striker before releasing it to fire the round. Some pistols have the striker pre cocked only a small to moderate amount and are much like DAO in a traditional hammer & firing pin pistol. Others almost fully pre-cock the striker and are much like SA in a hammer & firing pin pistol. Others yet have striker mechanisms that are much like DA/SA. Glocks are undoubtedly the best known SFA pistols; others include Springfield Armory XD, Walther P-99 / S&W99, S&W M&P and Sigma, Taurus Millenium, Mil. Pro, 24/7, and CZ 100.

All of what you say here is true, but I would submit that the term "Quasi-DAO" might be preferable because it covers everything from a Para-Ordnance to a GLOCK 17 to an SIG P229 DAK. I guess I don't like the term "Striker-Fired Action" in principle because, for example, the Walther P99, which is striker-fired, is available in DA/SA and true DAO configurations. On the other hand, the striker-fired Browning 1910 is SAO. In other words, whether the pistol is hammer-fired or striker-fired is not necessarily relevant to the trigger mechanism, unless I'm missing something.

Having said that, and acknowledging ahead of time that I'm not an expert and may well have overlooked some important point, great post! :)

[ugaarguy]

dont forget lda also it must be cocked but when its cocked it protrudes only a few mm's so im thinking that would classify as sa? or i dont know
Still a DA because the trigger pull both cocks (the rest of the way) the hammer and releases it.
For "Errata" you probably could make some mention of the new Taurus SA/DA trigger mechanism (I know it's confusing since Taurus recycles model names). And I'm not sure it really falls into the arena of triggers, but maybe a mention of things like the SFS Browning Hi-Power hammer?
Good call and CJ did a great job of explaining the Taurus SA/DA so I'll leave that as is.
These pistols are designed to fire the all rounds Single Action. If there is a failure to fire, these pistols have the capability to fire in Double Action mode (referred to as second strike capability: allowing a second strike on a primer, frequently firing it on the second attempt).
You folks check my facts, but I believe the DA/SA Walthers, DAK SIGs, and LEM HKs also revert to full DA to allow second strike capability.

Of note there is some debate as to the merit of second strike capability. Some argue it's a great thing. Others argue that a Tap-Rack-Bang is the correct response. That's just a note, but perhaps we can start a new thread to discuss?
All of what you say here is true, but I would submit that the term "Quasi-DAO" might be preferable because it covers everything from a Para-Ordnance to a GLOCK 17 to an SIG P229 DAK.
That's definetly a good way to say it short hand. I went with "DAO with reduced trigger pull" to keep it, hopefully, simple & approachable for folks who are new to guns.
I guess I don't like the term "Striker-Fired Action" in principle because...
I went with SFA because that's the term the Army and Air Force have used on recent RFPs and RFIs. I do agree with you that the examples you list illustrate the variety of ways the SFAs can seem to operate. However, the Springfield XD, as an example, is so far precocked that it's practically SA in operation. Yet the trigger pull must still finish cocking the striker the last little bit before releasing it. Technically it's still DAO by definition and by BATFE classification. Striker fired actions are just different and sometimes trying to describe.

Thanks to all who've contributed to the excellent discussion thus far. Please continue to expand and clarify the basic frame work of the thread.

[briansp82593]

i think glock's is quite unique, its striker fired but totally sa, when you pull the trigger all you do is release the striker, no da backup... so... sfsa :evil: striker fired single action, unlike other sf pistols that are cocked as the trigger is pulled, aka kahr and SAA

[ugaarguy]

i think glock's is quite unique, its striker fired but totally sa, when you pull the trigger all you do is release the striker, no da backup...
Actually that's not even close. The Glock striker is about 60% pre-cocked. The connector cocks it the rest of the way and then cams down to release it. The BATFE defines Glocks as DAO. The SA XD is 95%+ pre-cocked and its connector does the same as the Glock's - still DAO according to the BATFE. S&W has a lightened DAO that requires the slide cycling to pre-cock it in a traditional hammer & firing pin setup. In both mechanisms the trigger is still performing double duty (finishing) cocking & releasing the hammer or striker.

[CypherNinja]

I've always thought of SA, DA/SA, DAO, etc..... as a completely separate issue from striker vs. hammer.

A hammer swings about an axis, while a striker moves back and forth in a linear fashion. Details on how each mechanism is cocked and released is irrelevant.

I think its confusing and inaccurate to try to lump all the striker designs into one category. (regardless of various marketing campaigns;))

It should be "a striker is just a different type of hammer, and uses all the same types of trigger mechanisms listed above.

Just my .02 :D

[DougB]

I agree with Cypherninja - striker vs. hammer is a completely seperate issue from trigger function. I have an SW99 (the original trigger, now called "anti-stress" by Walther). It is striker fired, but the trigger functions exactly as a traditional double action (DA/SA) gun with a hammer. The first shot is fired double action (no pre-cocking). After that, the gun is cocked (single action). This gun has a decocker button, and functionally works exactly like a traditional DA/SA (Walter P38, PPK, CZ75D, and many others). The fact that it uses a striker rather than a hammer is irrelevant to the trigger function.

Other than that, and the fact that several of the gun models used as examples could fit into multiple categories depending on the particular trigger options selected, I think this does a good job of summarizing information that is confusing to many new shooters.

Doug

[ugaarguy]

I agree with Cypherninja - striker vs. hammer is a completely seperate issue from trigger function.
I agree with that as well. However, as I stated in post 12, I'm trying to stick with current military terminology; right or wrong it tends to trickle into the civillian lexicon and get ironed out there.
I think this does a good job of summarizing information that is confusing to many new shooters.
Thank you for the encouraging words. My hope was to help shooters get a simplified view of how various guns operate. As with anything once the basics are grasped the details and technicalities can be discussed & debated. Hopefully this will help people to both understand how their handgun works, and clarify many of the terms discussed in the gun culture.

Thank you to all who've contributed thus far, and thanks for keeping this a great resource with civil discussion.

[Kowboy]

Ugaarguy:

Thanks for the great read, now may I ask for more?

Are there any computer animated videos that would show these different actions? I'm kind of a visual guy.

Thanks again,

Kowboy

[JohnKSa]

Glock Animations:
http://www.genitron.com/glock23/intglock.html
http://www.sniperworld.com/glock/

Beretta 92FS Animation: (Sorry, there is no provision to demonstrate DA operation)
http://www.genitron.com/IntPistol.html

1911 Animation:
http://www.m1911.org/loader.swf
http://www.m1911.org/full_1911desc.htm (page has several animations)

[BrokenArrow]

The terms are getting harder to nail down as the technology advances. Hammer and striker fired guns can both be SAO, DAO, or DA/SA(TDA).

IIRC, the BATF called the HS/XD a SA pistol. Why IDPA puts in a different class than the Glock.

Federal and civilian RFP definitions are all over the place. Things changed as the Army's FHS merged w SOCOM's SOF CP into the JCP that went back to CP and was then indefinitely postponed... for example from the Q&As on the JCP RFP :

51. Item 3.4.1 Action. Will all Striker Fired Actions be considered Double Action Only regardless of what the striker does during the action of pulling the trigger? Is there any Double Action definition as to what makes it a DA or DA pull? How will Double Action be defined?

Answer: The specification will be changed to state: DA/SA is defined as an action that sets and releases the sear with the first pull of the trigger, with subsequent shots being single action, only releasing the sear from a preset position, to fire the weapon. DAO/ Striker Fire is defined as an action that sets and released the sear with every pull of the trigger. Note: Any Striker Fire action that fully sets the sear will be considered DA/SA.

63. What do you mean by "Modular Action" and what will be required to for it to be considered changed. Item 4.4.1 states that the JCP must be able to be able to be changed from DAO to DA/SA, and back. If this is the case, how does the striker fired guns fall into this category? If the gun must be reconfigured from "Striker-Fired Action" which is considered DAO to a DA/SA gun which requires both a cocking action trigger pull and a pre-cocked action trigger pull as well as a de-cocking lever and external safety lever. I would appreciate some clarification on this matter.

Answer: Modular means that the action on the pistol can be changed at the unit level without modification to the weapon’s major assemblies from DAO to DA/SA, or DA/SA to DAO and back.

How about this?

3.4.2. Trigger Pull: ...When pressure is applied to the JCP trigger and then released, the trigger shall reset to its forward-most position, even if the pistol is not fired (T). The operator shall be capable of pulling the trigger, without shifting the firing grip as will be tested in section 3.6.3.

What the heck did they mean by that? Could read it in a way that leaves the Glock and XD out in the cold (second strike? can't cycle slide to reset striker?)

The DHS in 2004 made it very simple:

3.2 Operation: The pistol shall be an action that provides smooth and consistent trigger pull for the first shot and all consecutive shots.

SIG(DAK), HK(LEM), Glock(SA), XD(USA), S&W(DAO), and Beretta(DAO) entered. Bertta withdrew early. When the smoke cleared after firing about 3 million rounds in 9/40/357 through about 300 test pistols, only SIG and HK got contract options for up to 65,000 pistols over 5 yrs.

Will be interesting to see how they define things for the next go in 2009, who enters, and who passes.

[mekender]

i believe that the new ruger is also a striker fired weapon

[polekitty]

Recently I bought a Taurus 24/7PRO. It has a SA/DA trigger system with “re-strike” capability. Frankly, I think I would not bet my life on that re-strike. If the cartridge failed to fire the first time it might do it again on the second try. I don’t think I want to keep hitting that “dead” cartridge over and over while the other guy is making holes in me! I’ll rack the slide ASAP and go for a new load!

[gunboat57]

One more comment on the Taurus 24/7 Pro. When firing "SA" the striker is held about 95% of the way back by a sear. Pulling the trigger pushes the sear rearward, compressing the striker spring a bit more while the sear is cammed down to release the striker. It's like a Glock with more precompression. It sorta blurs the distinction between DOA and SA/DA.

[Mad Magyar]

In what category do you place the Daewoo in "Fast-Action",a.k.a. "Tri-Action"?

[ugaarguy]

In what category do you place the Daewoo in "Fast-Action",a.k.a. "Tri-Action"?
Mad Magyar, The Daewoo Fast-Action/Tri-Action is a truly unique mechanism. It doesn't really fit into any of the major categories because it can operate several ways. Perhaps you or someone with a good bit of experience with one would write a post explaining it. It deserves a good explanation because it's such a unique system.

[Mad Magyar]

Fast Action Trigger System:
In a nutshell, here's how it works. A round is chambered and the pistol is cocked. The hammer is pushed forward with a thumb and then engage the ambidextrous safety. When the safety is disengaged, the hammer automatically springs into the cocked position for a single-action press of the trigger. There is no longer the heavy double-action 1st shot to contend with. Trigger pull is consistent from first shot to last. These systems are incorporated in the DAEWOO Fast-Action and Para Ordnance Light DA pistols.

[USMCDK]

I never thought a decocker could fail to stop the weapon from firing... wouldn't that mean it's not the decocker though but more likely the safety???

[Shawn Dodson]

DA/SA - Double Action / Single Action. These pistols fire the first round Double Action, and all following shots are fired single action. They generally use a decocking lever to safely lower the hammer, but block contact with the firing pin so the chambered round is not fired.
Caution Decockers can fail, so always point the pistol in a safe direction when decocking. Decocker failures are rare in modern firearms, but do occasionally happen. Some older designs are more prone to failure. If you have any doubt that a decocker is not working properly have the firearm checked by a competent gunsmith or armorer. This describes a conventional DA pistol. It is DUMBED down terminology for people who don't understand how a DA automatic operates. In MOST cases the hammer can be manually cocked to fire the first shot in SA mode, so they're not really "DA/SA" are they?

DAO with reduced trigger pull - These are the new breed of DA pistols, pioneered by Para Ordnace's "LDA" - Light Double Action. These pistols keep the hammer down, but cycling the slide pre-tentions the main spring / hammer spring. The result is a lighter weight DAO trigger pull, and some also provide for a shorter trigger pull & reset. Some also have the ability to revert back to a full weight DA trigger pull to give a second try if the round does not initially fire - this is known as restrike capability. Beyond Para's LDA, examples are SIG's DAK, H&K's LEM, and some Kel-Tec and Smith & Wesson Pistols. Edit: It has been brought to my attention that the hammer rests in a partially cocked position on the Kel-Tec PF-9, P-32, and P3AT; and possibly a few other pistols as well

Blah, blah, blah, what a bunch of technical marketing gobbledygook! They're DA or DAO. Period. The trigger mechanism performs the same function as DAO - cocking and dropping the hammer. Restrike capability? More marketing nonsense for the uninformed. If the pistol doesn't fire when you press the trigger then you immediately tap, roll & rack to clear the stoppage.

SFA - Striker Fired Action. These pistols use a Striker, basically a hammer & firing pin in one. Most operate similarly to a lightened Double Action. Cycling the slide partially pre-cocks the striker, and the trigger pull finishes cocking the striker before releasing it to fire the round. Some pistols have the striker pre cocked only a small to moderate amount and are much like DAO in a traditional hammer & firing pin pistol. Others almost fully pre-cock the striker and are much like SA in a hammer & firing pin pistol. Others yet have striker mechanisms that are much like DA/SA. Glocks are undoubtedly the best known SFA pistols; others include Springfield Armory XD, Walther P-99 / S&W99, S&W M&P and Sigma, Taurus Millenium, Mil. Pro, 24/7, and CZ 100. The trigger mechanism is DAO regardless of striker or hammer fired. Pressing the trigger cocks and drops the striker/hammer.

There are three different types of trigger mechanisms:
1) SA
2) DA
3) DAO

Anything else is marketing gimmick or ignorance.

Cheers!

[JohnKSa]

The trigger mechanism performs the same function as DAO - cocking and dropping the hammer.No, Shawn, it doesn't and you know it doesn't.

Before this new breed of pistol was invented a DA had to trigger cock the hammer against the force of the mainspring. These pistols don't fight the mainspring with the trigger pull because the slide does that work. Therefore the trigger only has to move the hammer without working against the mainspring. It's a different way for the trigger to function and that's why the trigger is so light even though it may seem to operate like a conventional DA from the outside.Restrike capability? More marketing nonsense for the uninformed. If the pistol doesn't fire when you press the trigger then you immediately tap, roll & rack to clear the stoppage.Restrike capability is defined correctly in the blurb you quoted. You may not agree with using restrike capability (and you may even have a good point in that regard) but it doesn't change the definition of restrike capability. And while your statement about what to do if a cartridge fails is a position that is held by many, it's not one that is universally held--nor is everyone who advocates the use of restrike capability uninformed.The trigger mechanism is DAO regardless of striker or hammer fired. Pressing the trigger cocks and drops the striker/hammer.Well, it is DAO unless it's not. And pressing the trigger cocks and drops the striker/hammer except when it doesn't.

As you already know, not all the guns mentioned in the blurb you quoted have a trigger that will cock the striker/hammer, in fact most of them will not do so. As you know, most of the guns listed require the slide to tension or partially tension the mainspring before the trigger will do anything at all. And you know that's not the way a true DA or DAO behaves because you stated correctly that a DA or DAO has a trigger that cocks and drops the striker hammer.

I suspect that you do actually realize why people might want to understand why a gun that is often called DAO operates more like a SA (externally speaking) in that it requires that the mechanism be cocked by slide action before the trigger will operate.Anything else is marketing gimmick or ignorance.Interesting gambit.

So either we agree with you or we're ignorant and/or spouting "technical marketing gobbledygook".

I'm curious--do you "pre-insult" those who disagree with you in an attempt to prevent anyone from posting a differing opinion or do you truly believe that anyone who disagrees with you is automatically mistaken?

[Shawn Dodson]

Before this new breed of pistol was invented a DA had to trigger cock the hammer against the force of the mainspring.

Agreed, the mainspring is indeed under tension. However if the hammer is UNCOCKED then one must press the trigger to cock and drop the hammer (to fire in DA mode). The mechanical shock required to ignite the primer can only be delivered by a fully cocked hammer. Therefore it is simply DA. The amount of trigger pressure may be reduced but the hammer MUST be cocked to deliver adequate mechanical energy, either manually or by operation of the slide or by pressing the trigger - just like any other DA pistol.

Restrike capability is defined correctly in the blurb you quoted.

I described restrike capability as marketing nonsense. That's it. I didn't re-define it. The term "restrike capability" is used in the defense pistol industry and it's presented as an advantage when it's not. If the gun doesn't go bang with the trigger is pressed then the problem is more likely something other than a misfire (empty chamber, failure to feed, unseated magazine, failure to eject). It encourages a user to keep pressing the trigger in the hopes that the gun will eventually fire, instead of taking immediate, positive action to get the gun back up and running. Hence "marketing nonsense."

For example, the M4 carbine doesn't have restrike capability. Neither does the 1911A1.

As you already know, not all the guns mentioned in the blurb you quoted have a trigger that will cock the striker/hammer, in fact most of them will not do so. As you know, most of the guns listed require the slide to tension or partially tension the mainspring before the trigger will do anything at all. And you know that's not the way a true DA or DAO behaves because you stated correctly that a DA or DAO has a trigger that cocks and drops the striker hammer.

This is how Glock describes their trigger mechanism:

"The “Safe Action” system is a partly tensioned firing pin lock, which is moved further back by the trigger bar when the trigger is pulled.

"When the trigger is pulled, 3 safety features are automatically deactivated one after another. When doing so, the trigger bar is deflected downward by the connector and the firing pin is released under full load. When the trigger is released, all three safety features re-engage and the GLOCK pistol is automatically secured again."

Pressing the trigger cocks and drops the striker. Period. The striker obviously cannot be manually or automatically cocked to operate in SA mode.

Operating the slide merely resets the trigger mechanism, which requires tension to maintain positive contact to ensure positive operation. The fact that the striker is "pre-tensioned" does not make it different from any other DAO auto pistol. Press the trigger and it cocks and drops the striker. It does not fire from the "pre-tensioned" position alone otherwise there'd be no need to retract it to "full load" position by pressing the trigger.

(If it were capable of firing from the "pre-tensioned" position alone then it would be an SA mechanism like the 1911A1.)

A Beretta 96SF can be fired, in DA mode, with the hammer in half-cock (i.e., "pre-tensioned"). Should new terminology be invented to describe this ordinary DA trigger function? Install a factory DAO 92D mainspring and one can convert it into a Beretta 96LDA!

How much trigger pressure required is irrelevant - if you press the trigger and the hammer or striker moves backward, then the trigger mechanism is either DA or DAO.

The purpose of marketing is to convince you that product features are unique and superior to competing products.

[JohnKSa]

Agreed, the mainspring is indeed under tension. ... just like any other DA pistol.I took out all the verbiage in between to demonstrate exactly why it's NOT "just like any other DA pistol." ;)The term "restrike capability" is used in the defense pistol industry and it's presented as an advantage when it's not. ... Hence "marketing nonsense."As pointed out earlier, not everyone agrees with you, there are informed people who take a different view. Hence a difference of opinion. There's a difference between saying you wish to present different view (one that is not without merit, by the way) and saying that anyone who disagrees with you is spouting nonsense.Operating the slide merely resets the trigger mechanism, which requires tension to maintain positive contact to ensure positive operation.Been through this with you before so I know that you know the truth. I've even posted pictures demonstrating that the slide does NOT merely "reset the trigger mechanism", it does about 50% of the compression of the mainspring while the trigger does what's left. If you would examine a Glock with an open mind you would realize that's FAR more than would be required to "ensure positive operation".The fact that the striker is "pre-tensioned" does not make it different from any other DAO auto pistol.It's not just pre-tensioned, it's half-tensioned. And unless all DAO autopistols use the slide to put the hammer at half-cock or half-tension the mainspring then it does make it different from other DAO auto pistols.

But that's just one example out of the entire range of designs you blithely dumped into a single bucket. Some of the designs require the trigger to do all the work of tensioning the striker and don't require the slide to reset the action before the trigger can be pulled again. Others have the slide do almost all the work of tensioning the striker spring. What you're saying is that none of that makes any difference whatsoever.

That's an interesting opinion, but that's all it is. And again, it's certainly not an opinion that is universally shared. Not by any means.A Beretta 96SF can be fired, in DA mode, with the hammer in half-cock (i.e., "pre-tensioned"). Should new terminology be invented to describe this ordinary DA trigger function? Install a factory DAO 92D mainspring and one can convert it into a Beretta 96LDA!You would have a point if the gun were actually designed so that the slide action put the hammer in half-cock for each shot and the slide action was required before the trigger would operate. It doesn't work like that so the analogy fails and fails badly.The purpose of marketing is to convince you that product features are unique and superior to competing products.Would you say that is something like stating one's opinions as if they are fact?

[Johnny Guest]

Thanks to ugaarguy for his time and effort in writing up the original explanation. Thanks to the others who added their contributions and attempted to clarify the matter farther.

I feel, though, that the more this is thrashed out, the more invested some become in forcing everyone else adopt his own thoughts and nomenclature. Some things are, indeed, absolutes, and some are matters of opinion. I'm shutting down this thread before things become really ugly.

CLOSED

Johnny Guest
THR Staff