Striker fired works . . . how?

[Prof Young]

So in my recent post about shooting a Glock for the first time I noted that I might not be comfortable carrying one with out a safety. Here is the reason for my reservation.

As it was explained to me by the range master, when you pull the trigger on a Glock, you are RELEASING the striker. It was already cocked back by the last time the slide moved back, either in loading or from the previous shot. So that means in a loaded "racked" Glock you have a cocked striker ready to fly forward when released by the trigger pull. Sort of like carrying a single action gun with the hammer cocked. So the bottom line for me is I won't carry cocked unless it's also locked.

Do all striker fired guns work in this manner?

Lots to learn.

Life is good.
Prof Young

[TunnelRat]

Two factors to keep in mind. Glocks, like many other pistols, use a striker/firing pin block. This is a mechanical device that were the striker to go forward without the trigger being pulled (some kind of mechanical failure or severe impact) the striker is blocked from contacting the firing pin. It is disengaged by the travel of the trigger where an extension on the trigger bar depresses the mechanical block. Secondly, the little dingus on the trigger serves as an additional drop safety. The dingus is of such little weight that just a drop by itself isn't able to produce the momentum to depress the spring connected to the dingus. This means that just a fall won't drive the trigger to the rear and overcome the striker block. These two factors together make a Glock significantly more drop proof than a 1911 without a firing pin block, and even if the 1911 has a firing pin block there is some value in that dingus. Some designers, such as SIG most recently, have used other methods than the trigger dingus, with different levels of success.

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[FITASC]

No need for a safety on a Glock, there are enough measures in place; plus the safety between your ears. I prefer any non-1911 type of gun to not have any external extra safeties as it is one more thing to remember when milliseconds count. Glock, Kahr, HK P7, S&W revolvers and many others have excellent service records, all without the need for another lever to manipulate.

[TailGator]

In addition to the above factors, the striker on a Glock is only partially cocked. Different people give numbers between half and two-thirds, but the point is that the trigger finishes cocking it before it releases. That is why people argue about whether the Glock is single action or double action. Maybe 1.5 action should be the new choice.

Lots of people carry Glocks of various sizes without accident. For them, the trigger has enough length and weight to be safe, while being short and light enough to shoot easily.

[tangolima]

Originally Posted by Prof Young

As it was explained to me by the range master, when you pull the trigger on a Glock, you are RELEASING the striker. It was already cocked back by the last time the slide moved back, either in loading or from the previous shot.

I'm afraid this is not true. Glock action is generally classified as DAO. The trigger pulls striker back before releasing it. It is especially so for the first shot. Subsequent shots could be less if proper techniques are used.

All the safety features that come with Glock action guarantee that the gun only fires when the trigger is pulled. Are additional mechanism needed to disable the trigger? That's the debate.

Do you feel comfortable carry a loaded DA revolver with shrouded hammer? A Glock is basically the same. There is no shame to say yes or no. There is no conclusion to that debate.

Whenever I am asked this question, my answer is; one should not use a tool he is afraid of.

-TL

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[DubC-Hicks]

As stated, the Glock striker is not fully cocked like a single action. It is only partially tensioned. It also has a striker block keeping the striker from falling without pulling the trigger first. And a trigger safety to keep the trigger from moving back from inertia if it is dropped.

Some striker fired guns are actually fully cocked, the XD/XDm comes to mind.

[jmr40]

The trigger pulls striker back before releasing it. It is especially so for the first shot. Subsequent shots could be less if proper techniques are used.

NO!

The trigger pull on a Glock is exactly the same for every trigger pull. Yes it is technically DAO, but the striker is ALMOST completely cocked before you start pulling the trigger. In practice it is a SAO, but since it meets the technical definition of DAO it is approved for most LE agencies. Most will not allow SAO.

On a standard Glock it takes 5.5-6 lbs pull on the trigger after a short take up. EXACTLY the same pull weight as 95% of 1911's as they come out of the box. The difference is that 1911's don't have the take up. For subsequent shots you can slightly release the trigger for it to reset and not have to worry about the takeup. There are options for Glock triggers as light as 3.5 lbs from the factory and as heavy as 8-9 lbs. Aftermarket options are all over the place.

If a Glock or any other striker fired gun is carried in a holster that covers the trigger I don't mind that it doesn't have a traditional safety. But I don't always carry that way. For nightstand or glovebox duty I'd not use a Glock with a loaded chamber. Having the option of a 1911 style safety doesn't hurt a thing and as much as I like Glocks just as they are I'd think the option of having one would be a plus. The M&P has that option, it doesn't cost a dime more and the user doesn't have to use it. Or it can be removed. I'd like to have the option with a Glock.

[lee n. field]

---delete, already pretty well covered----

[tangolima]

Originally Posted by jmr40

The trigger pull on a Glock is exactly the same for every trigger pull. Yes it is technically DAO, but the striker is ALMOST completely cocked before you start pulling the trigger. In practice it is a SAO, but since it meets the technical definition of DAO it is approved for most LE agencies. Most will not allow SAO.

Trigger pull for subsequent shots can be made shorter if you do trigger reset. It is exactly same as first shot if you don't.

By the same token, subsequent shot striker pre-cocks more if you do trigger reset. The striker pre-cocks. No question there. I don't think it is quite "almost completely" when the trigger is not being pulled though. I did read that the amount of the initial pre-cocking was enough to set off a primer. It could be true but besides the point.

I am going do some measurements to see how much the crucifix travels before it let's go the striker. That will tell how completely the striker is cocked.

-TL

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[HighValleyRanch]

I 'm stumped by people resembling a glock to a revolver as DOA.
You are comparing a 5 pound trigger on the glock to a 10 or heavier on most revolvers.

I think a Kahr is a better comparison to a revolver trigger.

Most ND's on the glock happen from holstering, I believe.

I know of an ND happening from the habit of pulling the trigger to release the tension before putting the gun away. I never understand why Hickok45 does that every time with his glocks?

[74A95]

Originally Posted by Prof Young

So in my recent post about shooting a Glock for the first time I noted that I might not be comfortable carrying one with out a safety. Here is the reason for my reservation.

As it was explained to me by the range master, when you pull the trigger on a Glock, you are RELEASING the striker. It was already cocked back by the last time the slide moved back, either in loading or from the previous shot. So that means in a loaded "racked" Glock you have a cocked striker ready to fly forward when released by the trigger pull. Sort of like carrying a single action gun with the hammer cocked. So the bottom line for me is I won't carry cocked unless it's also locked.

Do all striker fired guns work in this manner?

There are lots of Glocks (and other striker fired guns) in law enforcement duty holsters. As long as something covers the trigger to prevent accidental discharge, they are safe to carry with a round in the chamber.

[tangolima]

Originally Posted by HighValleyRanch

I 'm stumped by people resembling a glock to a revolver as DOA.
You are comparing a 5 pound trigger on the glock to a 10 or heavier on most revolvers.

I think a Kahr is a better comparison to a revolver trigger.

Most ND's on the glock happen from holstering, I believe.

I know of an ND happening from the habit of pulling the trigger to release the tension before putting the gun away. I never understand why Hickok45 does that every time with his glocks?

A glock's trigger pull can be easily increased to 10 lb. But it is still a Glock, pistol without manual safety.

-TL

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[JohnKSa]

...when you pull the trigger on a Glock, you are RELEASING the striker. It was already cocked back by the last time the slide moved back, either in loading or from the previous shot.

... the striker is ALMOST completely cocked before you start pulling the trigger.

Based on external measurements (tedious and time-consuming if one is concerned with achieving very accurate results) and on measurements made on a cutaway pistol (pretty simple), I managed to determine that the Glock striker spring is pre-tensioned about halfway (measuring spring compression distance) by the slide with the remainder of the cocking operation completed by the trigger.

So, by spring compression DISTANCE, it's about half and half between the slide and the trigger pull.

However, spring compression energy is not linearly related to spring compression distance. In terms of spring compression ENERGY, the slide does about 25% of the work of storing energy in the striker spring with the trigger pull doing the remainder of the work--about 75%.

It is true that the Glock trigger pull is the same every time the trigger is pulled, however, by holding the trigger to the rear when the gun is fired and only releasing to reset after the slide cycles, the shooter can enjoy a shorter trigger pull. Because the trigger is being held to the rear, the slide does ALL the pre-tensioning when it cycles. Now the shooter can just release the trigger slightly until it resets and then pull the trigger to release the striker. In this way, the amount of trigger travel is reduced although the trigger pull weight will still be identical.

And, of course, if the trigger is fully released, the tensioning is reduced back to the roughly 50%-distance/25%-energy pre-tensioned state which is achieved by the slide movement.

The Glock system is neither DAO nor SAO although it incorporates certain aspects of both classifications.

It is similar to a DAO design in that the trigger does a significant amount of the cocking operation for each and every shot. This means that the gun, internally, operates like a double-action only design in that the gun only fires after the trigger "cocks" the striker.

It is similar to an SAO design in that the slide MUST be operated for each shot, either by the shooter or by recoil. The trigger, once pulled is "dead" until the slide is operated. This means the gun acts very much like an SAO design which must be "cocked" by means other than trigger action before it can be fired with the trigger.

Obviously, it is also dissimilar to both an SAO and a DAO for the same reasons listed above. The BATF considers it to be a DAO design based on whatever criteria they find important.

Other striker-fired designs may work very differently. I am aware of several that operate in a manner generally similar to Glock's design as well as a few that operate very differently. Of the latter, some have the trigger doing ALL the cocking work while some have the trigger essentially just releasing the striker after the slide does all the cocking work.

As this thread shows, it's not always obvious how a particular striker-fired design operates and the various manufacturers are often not particularly forthcoming with the information. After hearing various stories about how Glocks worked, I spent a good deal of time some years ago trying to determine the details for myself. I compiled the results into a 28 page document with roughly 2 dozen annotated photographs and a handful of tables. I occasionally use it for reference.

[tangolima]

My measurements on my gen3 G23 concur with johnksa.

Release point to striker relaxation point. 0.285".

Release point to crucifix rest point. 0.148".

Release point to trigger reset point. 0.01”.

Pre-cocking is about 50% in compression length, or 25% in potential energy. I wouldn't call that almost complete.

Trigger reset increases pre-cocking to 96% in compression, or 93% in energy.

It is not really a DAO. It is a neither DAO nor SAO. It should be called Glock action.

Some claimed the normal pre-cocking could ignite a primer. I kind of doubt that.

-TL

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[kozak6]

The Glock is partially pretensioned, in some ways not entirely unlike carrying a half-cocked pistol. Modern Glocks are impressively drop safe, but carry concerns are generally directed towards the moderate trigger and a lack of an active safety. Unintentional discharges have resulted from defective/worn holsters, or from zippers and such getting caught in the trigger guard upon holstering. Sometimes, this results in a case of what is known as "Glock leg".

Do all striker fired guns work in this manner?

Nope. There are SAO strikers, DAO strikers, SA/DA strikers, and partially pretensioned strikers.

It is not really a DAO. It is a neither DAO nor SAO. It should be called Glock action.

"Safe Action" .

Some claimed the normal pre-cocking could ignite a primer. I kind of doubt that.

Depending on configuration it probably could, except it would require failure of the drop safety. Modern Glocks ace the frisbee test, so that's not so much a concern these days.

[elde]

Thank you JohnKSa. That's the best, most concise, understandable explanation of Glock trigger/striker operation I've read - and I've been carrying Glocks for 28 years now.

One question: I've been curious with regard to the trigger/striker operation of the Sig P365. I've not been able to determine whether that system is fully cocked or partially cocked. Would you have any idea as to the operation of this pistol?

And thanks again for the Glock information!

[TunnelRat]

Out of curiosity, has anyone actually conducted a test of whether the Glock striker at rest has enough energy to detonate a primer? I completely agree with John's comments above, I'm just curious if someone has been able to do such a test. I imagine if you removed the striker block it might be possible? Obviously not with a live round, if just a primed case.

[tangolima]

I read somewhere report of such test. I believe this is how it was done.

The striker block is removed. A primed brass (no powder, no projectile) is chambered. The back plate on the slide is replaced with a armorer's observation back plate, the one that exposes the crucifix. Without pulling the trigger, use a dental pick to press down the crucifix to release the striker.

The report claimed that the striker ignited the primer repeatedly.

-TL

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[Jim Watson]

Now we have the mechanical engineering out of the way, I advise the OP not to use a gun he is afraid of.
There are too many options; XD with grip safety, Plastic M&P with thumb safety that I can think of offhand, not to mention all the old fashioned hammer fired guns with DA start or manual safety.

[RickB]

If a Glock or any other striker fired gun is carried in a holster that covers the trigger . .

That's the real issue; most of the ADs with striker-fired guns of which I'm aware, including a shooting buddy with a limp, resulted from holstering the gun.
No matter how many passive safeties there may be preventing the gun from firing if it's dropped, firing if an internal part breaks, etc., the gun will fire if the trigger is depressed, which means there is no safety.

I've examined some Glocks with 3# triggers that had the dingus/dongle removed or rendered inoperable, and consider that only very slightly less "safe" than a stock pistol.

[Prof Young]

This is why I like this forum. You learn a lot.

I appreciate all the info. Can't say I'm "afraid" to carry a striker fired gun with no safety, but if I do I want the knowledge about how to do so safely. Local hardware store has a small (380) Glock in the case. I can't recall the exact model. May pick it up and compare to my Sig 238 and my Pico, to see if it may be a better carry choice for warm weather. I shoot the sig pretty well, but the Pico not so much. Of course both are mostly close range guns, but I do a lot better at a distance with the sig then the pico.

Life is good.
Prof Young

[Onward Allusion]

Glock you have a cocked striker ready to fly forward when released by the trigger pull. Sort of like carrying a single action gun with the hammer cocked. So the bottom line for me is I won't carry cocked unless it's also locked.

It ain't fully tensioned. Pulling the trigger completes the cocking. No different than carrying a revolver, except a Glock has a 5.5 lb trigger, whereas a revolver usually has a 10 to 12 lb trigger. If you are that concerned about it, then don't carry striker fired semi autos. Otherwise, you can drop a heavy trigger disconnect, a lighter trigger spring, and a heavy striker spring into a Glock. You'll up the trigger to about 8 to 9 lbs.

[JohnKSa]

One question: I've been curious with regard to the trigger/striker operation of the Sig P365. I've not been able to determine whether that system is fully cocked or partially cocked. Would you have any idea as to the operation of this pistol?

I'm sorry, but I have not had the chance to handle one or examine it to see how it works internally.

Out of curiosity, has anyone actually conducted a test of whether the Glock striker at rest has enough energy to detonate a primer?

It won't fire from the "at rest" position as there is no tension at all on the spring in that position.

I'm pretty sure that's not really what you were asking. Is there enough energy at the "pre-tensioned" position? I have seen a couple of claims that it can. To do the test properly requires bypassing internal safeties since it is not possible to drop the striker from the pre-tensioned position in a properly operating and fully assembled Glock without deforming/damaging parts.

This thread relates the experience of one person who performed the test properly and found that the gun would fire from the pre-tensioned position. I just replicated the test with a single primed cartridge (Federal) and it did fire. The firing pin strike was clearly light, but the primer did go off.

It is not a perfect test as it requires removing the firing pin safety from the slide. Even with the trigger bar pushing up on the firing pin safety, there is still some minor interaction and therefore some friction between the striker and the firing pin safety plunger. That friction isn't there with the firing pin safety completely removed.

I'm not going to claim that friction would be enough to change the test results, just pointing out that the test doesn't perfectly replicate what would happen in a fully assembled Glock with the firing pin safety installed but somehow deactivated.

So it does seem that it is possible, under at least some circumstances, that a Glock striker spring has enough stored energy in the trigger forward position to fire the gun. It's sort of an academic result as the internal safeties will prevent that from happening, but it is interesting.

The striker block is removed. A primed brass (no powder, no projectile) is chambered. The back plate on the slide is replaced with a armorer's observation back plate, the one that exposes the crucifix. Without pulling the trigger, use a dental pick to press down the crucifix to release the striker.

I have seen this test described but it is not really a good one as it may damage the gun. The ramp safety is designed to prevent the cruciform from moving down enough to release the striker until the trigger is pulled. To get the striker to drop with this test, the ramp safety and/or the cruciform must be deformed/flexed/compressed to at least some extent. What is likely happening is that as the cruciform is being forced down, it is also inadvertently being pulled to the rear so that it can clear the ramp safety. Pulling the cruciform to the rear tensions the striker spring just as pulling the trigger does.

A better test is the one described in the thread I linked to. It requires working with the slide removed from the pistol which bypasses the ramp safety entirely.

[JJ45]

I am also interested in the OPs second question; "Do all striker fire guns work in this manner"?...What is the difference between a Glock and XD firing mechanism?

[tangolima]

Originally Posted by JohnKSa

I have seen this test described but it is not really a good one as it may damage the gun. The ramp safety is designed to prevent the cruciform from moving down enough to release the striker until the trigger is pulled. To get the striker to drop with this test, the ramp safety and/or the cruciform must be deformed/flexed/compressed to at least some extent.

You are right. I tried this myself just now, and it didn't work. I think the experiment was done with a modified cruciform. Part of it was cut away so that it could be pressed down with a small tool.

-TL

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