The M&P trigger is hinged. The Glock has that little "thingy" in the middle. The Apex upgrade is the same as the Glock. I'm sure there are other guns in the world with this same setup. The idea behind it is, if that thingy isn't pressed, the trigger can't physically move.
Does anyone here actually believe that it adds to the safety of the gun?
I mean, if the idea is to stop the trigger from moving, it won't. ANYTHING that gets in there will press that thingy and allow the trigger to move and subsequently fire.
IMO the Apex/Glock "thingy" is a little better. The S&W trigger could get pushed by external influences easier since the whole bottom half of the trigger pivots where the Apex/Glock has the lever in the middle of the trigger so if something caught the edge of the trigger it wouldn't move to the point of discharge. That being said, it's only the first element of the safety, once you get past the trigger block (either system) there is still the striker block. I suppose if you caught the trigger on a pocket loop and then kept pushing it until you shot yourself in the leg it could happen. All the fitting instructions with the holsters I've bought have a "cocked and unloaded" drill to ensure that the holster won't fire for some reason. IIRC, the Apex instructions say the same thing.
Although the device is marketed as a "trigger safety," as Jeff Cooper pointed out with the Glock, putting the safety on the trigger is like putting the combination on the vault door.
One purpose of the device is, most assuredly, to help to prevent inadvertent discharge.
You will, however, note that for the most part such devices are only present on STRIKER fired pistols and not on hammer fired pistols.
The reason the device is ever present on striker fired pistols is because of the possibility of inertial discharge in case of a drop on the REAR (rather than muzzle) of the pistol.
Historically, engineers figured out that semi-autos could discharge if dropped on the MUZZLE as the only thing holding back the firing pin was the firing pin spring. A heavy steel firing pin, in combination with a spring that is worn, in combination with a drop onto the muzzle from a sufficient height results in a BANG.
Colt figured this out well before WWII and one of its engineers, William L. Swartz, filed a patent application on 4-13-1937. The so-called Swartz safety was patented on 12-20-1938, patent number 2,140,946. The device was licensed to Colt's Patent Fire Arms Manufacturing Company, Hartford Connecticut. The Swartz Safety was an internal firing pin block which was deactivated when the grip safety on the 1911 was depressed.
The device was put on some pre-war 1911s (I have seen it more often on .38 Supers), but it was expensive and WWII came along, and the device was not put into war time production, nor was it added back after the war.
The weak point of its design was that it worked off the grip safety. Some thought that was its strong suit. In any event, when Colt introduced its Series 80 improvements, things were getting less business friendly from a litigation standpoint, and so a device to prevent discharge was needed in case the 1911 was dropped. Colt re-designed the Swartz Safety into the Series 80 firing pin block we know today, which differs from Swartz' patent in that the Series 80 works off the trigger as opposed to the grip safety. It is a more positive system. It was initially criticized as making a light trigger more difficult to achieve, but the only place this rumor still persists is on the internet.
The Series 80 system patent ran out and now Remington, Para, Umarex and others use it. Kimber uses the Swartz system as did S&W on its original 1911s. S&W's new system, like Springfield and many others, now use a very light titanium firing pin combined with a heavy firing pin spring to survive drop testing. Colt uses this method on its Series 70 reproduction guns and anything that does not have the actual Series 80 firing pin safety.
The main purpose of the firing pin block is to prevent inertial firing in the event of a drop on the muzzle. The firing pin block was introduced to "modern" pistols with the West German police pistol trials in the 1970s, which produced the Walther P5, the SIG P6 (commercial 225) and the HK P7 (PSP, P7, P7M8, etc.).
SIG and Walther put the firing pin block into its designs, which were, in compliance with the West German requirements, designed to have no safety lever in the traditional sense. S&W's 1st Gen Autos had the P38 style safety, which decocked the pistol and arrested the firing pin when in the ON position (down). Designed to prevent inertial discharge in the safe position, NOTHING was present to prevent inertial discharge in the event the slide mounted safety of the S&W was in the fire position (up). Because it deactivated the trigger when on, the slide mounted safety/decocker, which was difficult to take off at high speed - much more so than the ergonomically better thumb safety lock on the 1911 - Jeff Cooper gave it the nickname "Dingus," leading to the Cooper dictum, "Don't get caught with your Dingus down."
As LE doctrine changed subsequent to the West German Police trials, agencies decided that the slide mounted safeties should be carried OFF, and S&W then designed its firing pin block into 2nd Gen and subsequent designs, including all current modern duty pistols (except the 1911 E Series, which uses the light firing pin method as explained) in order to prevent inertial discharge in the event the pistol was dropped.
Enter the striker fired mechanism. Glock knew that inertia works in both directions. A striker fired pistol in which a "trigger bar" is in contact with not only the lug on the firing pin, but also the firing pin safety, and which when drawn to the rear will hit a release point causing BOTH the deactivation of the firing pin safety and the release of the striker to run forward at high speed to fire the round presented a problem not present on hammer fired pistols.
Thus, something had to be designed into the system of the striker fired pistols which would prevent inertia from causing the trigger bar to travel rearward thereby deactivating BOTH the firing pin safety and causing release of the firing pin.
Because the pistol will discharge no matter what causes the striker to move far enough rearward, the extra device to prevent inertia firing was needed.
Inertia of the kind which can cause a discharge in the 1911 is normally thought of as a drop on the muzzle, the pistol stops suddenly, and the firing pin keeps moving forward. BANG. Certain rifles, such as ARs, AKs and M1As and M14s have this same issue. Slam firing is the term applied when the bolt runs forward on such a rifle at high speed, comes to a sudden stop, the firing pin keeps moving forward and the primer is dented. Usually not enough to cause a discharge, but if you have an extra sensitive primer, well - that is when your muzzle better be pointed in a safe direction. Some AKs for the US commercial market have firing pin springs designed to prevent slam firing.
Inertia works both ways. In a striker fired pistol, the firing pin safety prevents discharge if the pistol is dropped on the muzzle. However, if a striker fired pistol is dropped on its rear end, inertia can, and will, without the little articulating trigger, cause the trigger bar to keep moving to the rear. Of course, as it does so, the firing pin safety is deactivated and eventually, if the drop to the pistol's rear is with enough force, the trigger bar moves far enough back to its release point, and BANG.
In the event of a drop on the pistol's rear, there is no finger or anything else "pulling" the trigger, so the little articulating device does not get deactivated, and the whole trigger bar is not free to go flying rearward with inertia.
Now, all sorts of people will argue that it can't happen, the force is too great for an ordinary drop, etc. Not so. Please recall the Ruger SR9 was initially introduced without the articulating trigger safety. Very quickly, it was quietly redesigned and even the Ruger now has the device.
So, that is the real purpose of the device. Do you see why it is easier to merely call it a trigger safety? It would take pages of advertising to explain the above and few would understand it or care.
I hope that information was helpful.
EDIT: 8-7-2017
The SIG P320, just adopted by our military as the M17 and M18 pistols, seems to be the subject of a controversy.
Dallas PD stopped authorizing the pistols.
SIG and Dallas PD talked, concluded an officer misread or misunderstood a statement in a manual (perhaps an armorer's manual) and without any testing (apparently), SIG says all is well, and DPD is to resume authorizing the P320s.
Then, Omaha Outdoors drop tested the P320, and the results were so bad that Omaha Outdoors has suspended all sales of P320, at least as of the date of this edit.
Reaader's Digest Version:
It makes it possible for the M&P to pass the drop test phase where the gun lands on the rear end. Without the lock, inertia could cause the trigger to keep going and fire the gun.
Before you ask, the part that makes it possible for the M&P to pass the drop test where the gun lands on the muzzle is the Striker Block. It prevents the striker moving forward and hitting the primer.
All the safeties in an M&P are released when the trigger is pulled, so, no, it does not prevent shooting yourself by pulling the trigger.
This has been some very informative reading. I never realized that the trigger safety is there to prevent the trigger bar from deactivating the striker block if the pistol were dropped on its rear end. I always thought that the trigger's a silly place to put a safety. Thank you shawn mccarver and OKFC05.
Extremely well written and comprehensive explanation of the various safeties and their intended function. I hope you had that somewhere and pasted it...if not hats off to you for taking the time to educate us!
Much better explanation than I could have given .... (And some of the guys know how long-winded I can get....)
IMHO, the M&P's split trigger is a waste of small parts and an overcomplication. It's just not likely to do anything useful. The "little bar" setup, like the Glock, really isn't much better, but might be useful in a case or two per decade....
The Swartz safety (on the Kimber guns) is asking for trouble. The problem is that you can behead or seriously bend the little pin coming up from the grip safety and never notice it. I knew a guy who was an armorer for a Sheriff's Department out West who was forever getting guns back with "it don't work" from the field because his Deputies weren't careful about putting the slide back on. You have to pencil-test the gun after each disassembly.... While you could do that with a Colt Series 80 (the little "flag" that comes up from the frame to activate the button in the side is kinda lightweight), odds are you'd notice the mess you'd made.
IMHO, too, the Swartz block is a bad design. It's "L"-shaped, and the force coming up from the grip safety is reduced because it's coming from one side. Crud in there could slow it down or stop it from working. Meantime, you need to remove the rear sight to clean it....
I had the (mis)fortune to do a little work on a Llama .40 a while back. It would only fire some reloads one of our club members was making. Factory loads wouldn't ignite.... We pulled the Swartz block from the slide and noticed that it had been hit on it's rear "face" by the firing pin's notch in such a way as to raise a bump on the bottom of the block. That rode on the firing pin, and retarded it's movement. Our club reloader was using soft primers....
Fortunately, my little Kimber has no drop safety.... My other 1911's mostly do.
Useless, IMHO.... But I'd hesitate to carry a striker-fired gun without one.
A police officer shot himself at the gun range during his qualification re holstering his fire arm. It was raining that day and the pull string on his rain coat got caught in the trigger. Accidents can always happen.
To me, a safety is a device that prevents the weapon from firing if the trigger is pulled inadvertently. I know, I know, keep your finger off of the trigger. Well, other things can pull a trigger besides a finger, and that's why I like a thumb safety, even on an M&P.
IMO the Apex/Glock "thingy" is a little better. The S&W trigger could get pushed by external influences easier since the whole bottom half of the trigger pivots where the Apex/Glock has the lever in the middle of the trigger so if something caught the edge of the trigger it wouldn't move to the point of discharge. That being said, it's only the first element of the safety, once you get past the trigger block (either system) there is still the striker block. I suppose if you caught the trigger on a pocket loop and then kept pushing it until you shot yourself in the leg it could happen. All the fitting instructions with the holsters I've bought have a "cocked and unloaded" drill to ensure that the holster won't fire for some reason. IIRC, the Apex instructions say the same thing.
I agree. I just wish Apex would make the polymer trigger for the Shield. Last I heard from them, they said they weren't going to.
The M&P trigger is hinged. The Glock has that little "thingy" in the middle. The Apex upgrade is the same as the Glock. I'm sure there are other guns in the world with this same setup. The idea behind it is, if that thingy isn't pressed, the trigger can't physically move.
Does anyone here actually believe that it adds to the safety of the gun?
I mean, if the idea is to stop the trigger from moving, it won't. ANYTHING that gets in there will press that thingy and allow the trigger to move and subsequently fire.
What, if any, purpose does it serve?
It actually part if the drop safety, should the striker block fail, for whatever reason.
That's about as lucid and informative an explanation as I've seen in a very long time, Shawn. I've owned Glocks--a G22 and a G19, both second-generation--and liked them both, revolver guy though I am. But thinking back on them, I don't believe I was ever entirely comfortable with the lack of a manual safety or de-cocker. You clarified a lot of things.
But I'm back to revolvers, and will stay there unless someone just wants to give me a nice 3913, 469 or 1911, out of sheer generosity.
Ya I don't see how it really does much of anything! My first thought is that a child's finger would not be large enough to allow the trigger to be pulled and gun be fired but the way it''s made even a small child can fire the gun without thought or would make the trigger safer from things snagging onto it but I don't think that's the case at all if the hinge was lower on the trigger maybe it would make it better, safer with a more deliberate finger placement and press for it to fire.. IMO it doesn't do much and anything the way it is..I still think it's a safe gun that is if you don't pull the trigger the gun won't fire.. Yes you need to take common sense precautions too as with any gun! George
I re read the post and if the trigger thing is in fact there so it would pass the drop test when the gun is dropped on the rear then it surely has it's place! I never thought of it that way before.. Thank you for posting this info Shawn!
Extremely well written and comprehensive explanation of the various safeties and their intended function. I hope you had that somewhere and pasted it...if not hats off to you for taking the time to educate us!
It actually part if the drop safety, should the striker block fail, for whatever reason.
Atticaz:
The drop safety is intended to keep the striker from moving if it dislodges from the sear somehow. I don't see how the trigger safety - either the S&W or Glock version - has any effect on that.
It's purpose seems to be to keep you from fully depressing the trigger, and while the design, in a striker-fired weapon, is going to help keep the trigger bar (as in the M&P) from moving the striker block by itself, I don't see the contribution.
If there were enough inertia to move the trigger bar, wouldn't it also move the thing on the trigger thus disengaging the safety?
Quote:
Originally Posted by SMMAssociates
Atticaz:
The drop safety is intended to keep the striker from moving if it dislodges from the sear somehow. I don't see how the trigger safety - either the S&W or Glock version - has any effect on that.
It's purpose seems to be to keep you from fully depressing the trigger, and while the design, in a striker-fired weapon, is going to help keep the trigger bar (as in the M&P) from moving the striker block by itself, I don't see the contribution.
'Course, I'm always willing to listen ....
Regards,
If the trigger safety isn't disengaged then the trigger can't be pulled to move the trigger bar. Conversely, the trigger bar can't move unless the trigger safety is disengaged.
So if you think about that in the terms of a drop test and a failed or malfunctioning striker block, the trigger safety will still prevent the trigger bar from moving and the striker from being released. I suppose there is some formula in spring weight to safety weight that prevents the safety itself from inertial movement.
You are missing the point, the trigger safety isn't designed to keep you from pulling the trigger. It is designed such that the ONLY way to fire the gun is to pull the trigger.
Our chief shot himself in the leg holstering is MP 40sw compact. He is over weight and the top of the IWB holster sweat guard pulled the trigger . Ouch! Love handles and holsters with MP40C.
You are missing the point, the trigger safety isn't designed to keep you from pulling the trigger. It is designed such that the ONLY way to fire the gun is to pull the trigger.
If there were enough inertia to move the trigger bar, wouldn't it also move the thing on the trigger thus disengaging the safety?
This is a very good question, and an astute observation. As I am not sufficiently trained in engineering and the mathematics required to answer your question, I can only guess. But, it is an educated guess, based upon a discussion with an engineer at Glock. Apparently, the tiny blocking device in the trigger is so light in weight compared to the spring which holds it in place, that the tiny blocking device (in the S&W, the articulating part in the trigger) will not overcome the spring as it does not develop enough inertia. Glock has tested this out of helicopters and still could not overcome the spring on the little blocking tab. Sorry I cannot explain this part better.
I got a good explanation, just like you did from the other commenters here. The end result for me is that it does add SOME safety from being dropped and it is not complicated enough to cause a lot of trouble. Therefore, the two triggers doesn't bother me as much as they did so I would buy a gun with two triggers given no other choice. Education helped reduce the fear of something I didn't quite understand.
Extremely well written and comprehensive explanation of the various safeties and their intended function. I hope you had that somewhere and pasted it...if not hats off to you for taking the time to educate us!
I am sorry to report that I did not have it anywhere except in my mind. Thus, I had to write it to answer the question, which I was happy to do. I appreciate the kind words by you and by many others who were so complimentary of the effort to explain the device. Thank you.
Shawn: You said it perfect. Since it is so "light" ( think feather ) no matter how hard you hit/how high you drop it, you can not create enough inertia to overcome the heavy (think lead ) spring. Thank You for the explanation, I will reference it, giving you credit. Be Safe,
That explained it well enough. In fact, that was my thought as well, but I wanted to see if you had something more.
I'm very impressed by your explanation. A long time ago, I heard that Glock had added it to appease the crowd that was shouting about no external safety. Your explanation is better.
I honestly never thought about the gun possibly firing by being dropped on the back. In fact, I'm still kind of on the fence about the reality of it. Even so, your explanation answers my original question which no one had ever done before. Bravo!
Shawn: You said it perfect. Since it is so "light" ( think feather ) no matter how hard you hit/how high you drop it, you can not create enough inertia to overcome the heavy (think lead ) spring. Thank You for the explanation, I will reference it, giving you credit. Be Safe,
Ah hem .
Quote:
Originally Posted by tonyxcom
I suppose there is some formula in spring weight to safety weight that prevents the safety itself from inertial movement.
Just purchased a new SD9VE and this style trigger is totally new to me as all of my pistols have been either the "normal" single or single/double action and never owned a Glock, etc...
I hate not knowing how/why things do what they do and you cleared it up perfectly.
This is a very good question, and an astute observation. As I am not sufficiently trained in engineering and the mathematics required to answer your question, I can only guess. But, it is an educated guess, based upon a discussion with an engineer at Glock. Apparently, the tiny blocking device in the trigger is so light in weight compared to the spring which holds it in place, that the tiny blocking device (in the S&W, the articulating part in the trigger) will not overcome the spring as it does not develop enough inertia. Glock has tested this out of helicopters and still could not overcome the spring on the little blocking tab. Sorry I cannot explain this part better.
You're right that the safety is defeated when there is enough force to overcome the spring that holds the safety in place. Pulling the trigger easily exerts enough force to move the spring but the force caused by m x a may not do so quite so easily, due to the second component of any vector quantity: direction. Acceleration (and any resultant force due to F = m x a) have both magnitude and direction and neither one alone is sufficient to quantify what happens. By designing the safety so that its direction of motion is not collinear with the trigger's direction of motion, you ensure that the acceleration from a single impact on the gun cannot cause simultaneous consequential motion in the two pieces.
Suppose that you drop the gun onto a hard floor so that the acceleration is exactly collinear with the trigger's direction of motion. The trigger will experience force in the direction of its natural motion and if the force is sufficiently large, it will move the trigger bar, perhaps discharging the gun. Now, suppose that the safety moves perpendicular to the trigger's direction of motion (which is roughly correct). The massive acceleration due to the gun hitting the hard floor also induces a force (possibly a large force) in the safety, but since the safety doesn't move that way, it remains in place.
Now, suppose you drop the gun onto a hard floor so that the acceleration is exactly collinear with the safety's direction of motion. The acceleration is so large that the acceleration induces a force sufficient to overcome the safety's spring. This is still likely to be of no consequence because the direction of the acceleration is perpendicular to the trigger's direction of motion, meaning the trigger cannot move in that direction.
This is clever. If you drop the gun so that you could make the trigger discharge the gun, the safety does not move so the trigger's motion is blocked. If you drop the gun so that you could make the safety move, the trigger does not move. Is this foolproof? No. What S&W engineers are trying to do is reduce the probability of a sequence of events creating an unwanted discharge to levels so miniscule that they are "negligible", an engineering term that means "so small you can pretend it doesn't exist." The non-engineering world tends to view safeties in a more binary fashion: "They definitively stop accidental discharge." Well, no. They just reduce the chances to such small levels that they are unlikely to ever happen and if they do, the company can handle the litigation that might come its way.
Since the firing pin block is subject to the same principles, it is conceivable that the gun could be dropped in such a way as to overcome the spring force that holds the block in place. What is the device that acts as a "cross check" for it? Perhaps the sear, which releases the firing pin, and whose direction of motion is not collinear with the firing pin block. (Actually, the sear's type of motion is not similar to that of the firing pin block, being rotational.) And even if there is no "cross check", you can reduce the chances that an impact will dislodge the firing pin block by using a very stiff spring.
I came to this thread via the safety notice for M&P Shields, where the lack of physics and engineering comprehension was creating a suffocating environment. I hope that this explanation helps non-engineers understand why S&W wants every pistol inspected and why they use such strong language by insisting that every pistol in doubt be sent in for repair. The malfunction of the inertia safety greatly reduces the improbability that a single chain of events that start by dropping the gun can create an accidental discharge. As a Shield owner I won't accept the increased risk and I don't think anybody else should either.
Edit: Now that I'm holding my Shield 9 in my hands, I must amend some of what I said above. I stated that the inertia safety moves perpendicular to the motion of the trigger bar. This is incorrect. The inertia safety in the trigger rotates on the pin that holds it in the trigger. The part of the safety moved by your trigger finger -- the lower part of the articulated trigger -- moves in a direction similar to that of the trigger bar. The part above the pin does not. Because the motion is rotational (not linear) the part above the pin moves in the opposite direction.
Does this mean that dropping the gun in a fashion that could apply a force of sufficient magnitude and direction to discharge the gun by moving the trigger bar is also likely to move the inertia safety? No, it is unlikely. Why? Well, let's divide the safety into parts: the part above the pin about which it rotates, and the part below. Let's assume (incorrectly) that the mass and position above and below the pin is equal, yielding a center of mass exactly on the pin. Given acceleration due to dropping the gun, there will be no torque on the safety so it will not move. Now, let's assume that the mass and position above and below the pin are not equal; instead, let's assume that the mass above is greater and/or its distance from the pin is greater. This actually enhances the safety because it means that any acceleration that would move the trigger will try to move the safety even more toward the "safe" position, or opposite that of the direction in which your trigger finger pulls the pivot. While this is not the orthagonal geometry of which I wrote above, it is equally clever. And then, to further reduce the chances of the safety failing, you stick a spring on the safety that tends to pull the pivot toward the "safe" position. This is doubly clever.
My safety works just fine so my pistol requires no repair. For this I'm glad, and I also enjoy threads of this kind because we get to explore the physics and engineering of these magnificent devices.
Last edited by BuckeyeChuck; 08-29-2013 at 10:15 PM.
Thanks again BuckeyeChuck. That was very well said.
I had not considered the how the vectors were different for the trigger and trigger safety until I started trying to explain it in the other thread. This makes it very clear, at least for me.
To me, a safety is a device that prevents the weapon from firing if the trigger is pulled inadvertently. I know, I know, keep your finger off of the trigger. Well, other things can pull a trigger besides a finger, and that's why I like a thumb safety, even on an M&P.
+1. Once you are used to sweeping off a safety I don't know why you would not want one.
Seriously, if you're used to swiping off a safety, having one on another gun that more or less works the same way, or is missing entirely, shouldn't be a problem. If there is one, it's just your old training. If it's missing, it's kind of breaking training, but trying to switch it off when it's not there will likely be less disconcerting than forgetting to do that, or, worse, having to remember that it goes the other way!
I carry an M&P40C and M&P40FS around the house. Neither have the thumb safety. "Outside", it's a 1911. On the range, I'll flip the non-existent lever on the M&P's (when I can get some affordable .40's!; I"m reloading .45's right now, but need something like $200 to add another caliber) out of habit.
The only real downside, IMHO, is that the M&P design really doesn't gain anything from having a thumb safety (although the one on the Shield is supposed to be mightily stiff), and you can't flip a safety on while "handling" the gun or for whatever reason you might come up with.
I tried a thumb safety on the 40C for a while (actually used the bottom half of a 9C) and decided that it really didn't matter. When I decided to sell the 9C, I swapped bottoms back. (Then kept the 9C anyway....)
YMMV, of course. Probably the worst thing you can do is try to carry something with a safety that works backwards. I've retired my two older guns - an M39 and a PPK/S - that are so equipped. Like the M&P's, it's safe to carry these with the safety off, but the M39 is soft enough to change it's mind. The PPK/S won't.... (With both of those, you lose their fairly positive drop safeties that way, too, but that's another story.)
Does anyone here actually believe that it adds to the safety of the gun?
What, if any, purpose does it serve?
no.
suppose it prevents a drawstring or something like that from pulling the trigger if it gets wrapped around it and pulled up against the frame, but that's it. The real purpose is to make lawyers and others feel safer.
suppose it prevents a drawstring or something like that from pulling the trigger if it gets wrapped around it and pulled up against the frame, but that's it. The real purpose is to make lawyers and others feel safer.
You need to look at shawn's and BuckeyeChuck's posts. You'll see that you're wrong about that.
Here is a video that demonstrates what might happen when a gun is dropped on the rear of the slide:
When we were discussing this originally, some were questioning the physics of this. They didn't believe that dropping the gun on the back of the slide would generate enough force to move the trigger into the firing position; it does.
So, if you were ever thinking of defeating the trigger safety, don't. The life you save could be your own.
So where is all the smoke, sparks and flame (faked videos?)
Have you ever shot a blank? They also smoke. A real round would recoil like crazy. The fact that the trigger pulls back is one thing, causing a locked barrel and slide to actuate is something else.
I smell something really fishy about these videos. Did NBC make them?
I don't mind if someone proves something, but to add "dramatics" to pretend that the gun is actually shooting irks me.
Is the trigger really a safety?
.... (And some of the guys know how long-winded I can get....)
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