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Discussion Starter #1
I understand that the disconnector on a pistol allows the pistol to fire only when the trigger is pulled, preventing a semi auto pistol from malfunctioning into automatic fire. (I hope I'm right on that). What I don't understand is how it does it - how it works? Can someone explain? Thanks
mjohnson1
 

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Disconnector is for magazines; only allowing the pistol to fire if a magazine is installed.
 

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Actually what you are describing cowpokey is a mag disconnect. Found only in certain models like the Ruger SR series.

What mjohnson is asking about is the disconnector in the trigger that only allows the gun to fire another round after being reset by a forward movement of the trigger. I do not have the technical knowledge to answer this properly, but someone will be along who can.

I remember hearing a story of someone doing a homemade trigger job on a 1911 and disabling this function accidentally, turning it into a full automatic pistol.
 

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The disconnector disconnects the trigger form the sear while the action cycles forcing the need to release(reset) the trigger before the sear can be engaged again. In the case of the later models there is an additional disconnect operation requiring the magazine to be in place for the sear to be engaged to allow the firearm to fire.
 

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As above. But there are quite a few different disconnector mechanisms that accomplish this job. Exactly how they work varies among different pistols and rifles.

If you are asking about a specific model of firearm, you might be able to find a video graphic on-line that demonstrates the interaction of the trigger, disconnector, and hammer if you search hard enough. The mechanics are easier to understand visually than by describing the action in words.
 

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mjohnson1 said:
(ie. the disconnector on a pistol) What I don't understand is how it does it - how it works? Can someone explain? Thanks
That's a good question, because there are 2 basic types.

The first type allows the trigger to engage the sear ONLY when the bolt/slide is nearly fully forward (in battery). The Ruger Mark pistols have this type. When the bolt is moved rearward, the bolt forces the disconnector tab that moves the sear to be out of alignment with the sear. It won't allow the sear to be engaged by the trigger again until both - the bolt is fully forward AND the trigger is released. (The hammer plays no role in disconnecting with this type.)

The advantage of this type is there is a low probability of an out of battery discharge (OOB). The disadvantage is that you must dry fire the pistol to take pressure off the main spring for cleaning or storage.

The second type disengages the trigger/sear connection ONLY when the bolt/slide is almost to the end of it's reward travel. The Ruger Charger pistols have this type. As the bolt reaches the end of moving back (pushing the hammer back ahead of it), the hammer pushes the disconnector lever down to misalign the trigger/sear. It won't allow them to realign again until the bolt has moved part way forward AND the trigger is released.

The advantage of this type is you can take pressure off the main spring without ever having to dry fire. You just move the bolt part-way back until it's against the cocked hammer, pull the trigger, and gently close the bolt while the hammer rides it down. The disadvantage of this type is an increased risk of an OOB sending shrapnel flying out the ejection port.

Both types break the connection between trigger and sear until the trigger is released ==> semi-auto operation if the sear/hammer notch are mating up correctly.
 

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Let's start at the beginning by describing a "sear". A sear requires at least two parts …. one with a "notch" of some sort and the other being a sharp edge that locks into the notch, often called a "sear". The most simple form of a sear would be a single action revolver with a sharp rear trigger extension that fits in a hammer notch to keep the hammer cocked. Once the trigger is pulled to the rear, the sear will release and allow the hammer to thrust forward. This operation is good for exactly one round fired. If you want to fire again, the sear must reset by first allowing the trigger to travel forward and reset then cocking the gun again. We don't normally think of SA or DA revolvers or any gun that is not a semi-auto as having a "disconnector" but in actuality, all guns are designed to have them in one form or another.

Keeping with the same concept of "one shot per trigger pull", semiauto rifles and pistols need a way to prevent the gun from going "full auto". The device that does this is a "disconnector", which simply means the sear is disconnected and reset each time the gun is fired.

Some examples …. a Ruger MK series pistol uses a "trigger bar" as a disconnector. It connects the trigger to the sear. Once the trigger is pulled, the trigger bar will pull the sear forward to release it from the notch in the hammer. The hammer will release and thrust forward causing the gun to fire. As the bolt moves to the rear from blowback, the bolt will cam the trigger bar down and push the hammer back. This will cause the hammer to cock again, however the trigger must be released to reset and make the gun ready to fire again. So …. the process has three functions: the sear is released to fire the gun. The disconnector is actuated to prevent the gun from firing again, and the trigger springs forward to reset and start the cycle again.

A 1911 type pistol also uses a hammer with a sear notch. The trigger is coupled to the sear via a trigger bow. There is also a physical part called a "disconnector" that prevents the sear from releasing the hammer unless the slide is fully forward where the top of the disconnector rod enters a cutout in the slide. If the disconnector is held down for any reason, the pistol will not fire. This design by John Browning does two things …. it prevents the pistol from firing unless the slide is fully forward (full battery) and it also prevents the gun from going full auto.

Striker fire pistols and rifles also have a disconnector of some sort, depending on design. All disconnectors, no matter what type of gun, have one single mission and that is "one trigger pull, one round fired". Releasing the trigger allows the disconnector to reset and once both are reset, the pistol is again ready to fire. Some striker fired pistols operate more like a DA revolver but it doesn't matter … the pistol will still have a disconnector to prevent it from going full auto.

Full auto rifles have an "auto sear" that prevents the gun from firing when out of battery, however an auto sear does not require the trigger to be released each time, thus full auto operation.
 

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Pet Peeve

Nomadic Paladin said:
Actually what you are describing cowpokey is a mag disconnect. Found only in certain models like the Ruger SR series.
NP, you touch upon one of my pet peeves. Just like someone calling a magazine a clip, or calling a bolt a slide, Ruger incorrectly calls their magazine safety a magazine disconnect safety. It's not.

The Ruger mag safety blocks the sear just like the regular safety does and it does NOT disconnect anything. The Browning Buckmarks have a true mag disconnect safety. Removing the mag causes the disconnector to be pulled down thus breaking the connection between the trigger and sear. Personally, I think Browning's design is far superior to Ruger's. (And easier to disable - by just removing the link under the right side grip.)
 

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NP, you touch upon one of my pet peeves. Just like someone calling a magazine a clip, or calling a bolt a slide, Ruger incorrectly calls their magazine safety a magazine disconnect safety. It's not.

The Ruger mag safety blocks the sear just like the regular safety does and it does NOT disconnect anything. The Browning Buckmarks have a true mag disconnect safety. Removing the mag causes the disconnector to be pulled down thus breaking the connection between the trigger and sear. Personally, I think Browning's design is far superior to Ruger's. (And easier to disable - by just removing the link under the right side grip.)
Thank you, I learned something new today. My grandpa always said that any day you learn something new, you won't die in your sleep that night. I am safe for tonight.
 

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TestEngineer, Sorry but your description of a MK series disconnector is not correct. It was NOT designed for "out of battery" protection, It was designed just to prevent accidental full auto operation. If you check closely, most MK Series pistols will still fire when the bolt is about 1/4" from going to full battery, which will blow the head off a case …. not good enough to call it full battery protection. Most 22 semi autos, including the Charger (same as a 10/22) do not have any out of battery protection at all and will fire as soon as the bolt starts moving forward. The primary design for a 22 LR semiauto is "speed" meaning the bolt operates very fast so it doesn't leave much time for an out of battery condition unless a cartridge doesn't fully chamber. Further, another error …. the hammer in a MK series pistol is an essential part for the disconnector. If the hammer is not secured by the sear, the gun will go full auto. As you noted, Chargers and 10/22s do have a disconnector that requires recocking the hammer and releasing the trigger …. again, one trigger pull, one round fired. There are way more than two types …. maybe more like a dozen and they are not all used in semi autos. Even pump actions, lever actions, and even bolt action rifles have a disconnector of one type or another.
 

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TestEngineer, Another issue …. The way a MK III magazine disconnect works is like you described but in the overall scheme of things, it does indeed disable the sear unless a magazine is latched in place, thus a "MAGAZINE DISCONNECT". This generic term has been used at least since the Browning Hi-Power was released in 1935, maybe before. A rose by any other name is still a rose.
 

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Discussion Starter #12
Wow! - thanks everyone; I feel like I opened a can of worms? I get it somewhat. I should have indicated an application and did not. In earlier years I was a 1911 guy-had several; my favorite was a Colt Gold Cup;, then finally I found Kimbers. I my old age I am mostly Rugers; several 9 mms and those great Mark pistols-I have two Mark pistols and ordered another one today (22/45 Lite). I was wanting to apply the question to my Mark IV target and my soon to get 22/45 Lite. Thanks.
 

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Iowegan, Your post beginning with "Let's start at the beginning" was pretty accurate, but I must respectfully disagree with several things in your posts directed to myself. Starting with the latter one first...

Iowegan said:
TestEngineer, Another issue …. The way a MK III magazine disconnect works is like you described but in the overall scheme of things, it does indeed disable the sear unless a magazine is latched in place, thus a "MAGAZINE DISCONNECT". This generic term has been used at least since the Browning Hi-Power was released in 1935, maybe before. A rose by any other name is still a rose.
Any device that disables the sear, hammer/striker, firing pin, or trigger is a "safety". I think we can agree on that. However, a disconnector disconnects the trigger from the sear - thus preventing firing until the trigger has been released and subsequently reconnected to the sear.

If you have the thumb safety off and insert an empty mag into a Mark pistol while pulling the trigger, the hammer is going to drop. That's because the trigger is not disconnected from the sear. If you do the same procedure to a Buckmark pistol, the hammer will not drop. That's because the trigger is disconnected from the sear and can't re-engage it without releasing it first.

You can call a rose a magnolia if you wish, but it's still a rose. And a safety that doesn't disconnect the trigger is still just a safety - no matter who called it something it isn't.

TestEngineer, Sorry but your description of a MK series disconnector is not correct. It was NOT designed for "out of battery" protection, It was designed just to prevent accidental full auto operation.
At no point in my post did I say that the MK series disconnector was designed to prevent OOB discharges. But it is a practical side product of the design.

If you check closely, most MK Series pistols will still fire when the bolt is about 1/4" from going to full battery, which will blow the head off a case …. not good enough to call it full battery protection.
I've never seen a MK series pistol that will fire 1/4" OOB. Most need to be less than 1/8". I estimated the trigger on my mark pistols were being disconnected at 0.125", but wanted to know better than just a guess. So I designed a test to find out. I made an OOB shim and put it on an empty casing:



I placed it in the chamber:



I closed the bolt on it:



I pulled the trigger. And guess what? The trigger and sear were disconnected.

I repeated the experiment several times, trimming a little off the OOB shim until I could feel the disconnector tab just trying to catch the edge of the sear. Then I pulled it out and measured the shim again:



So the disconnector disconnects MUCH closer to 1/10" than to your stated 1/4". This is absolutely not protection enough to prevent an OOB from occurring, but it is small enough to prevent a lot of shrapnel exiting the ejection port. At least compared to the other type of disconnector that provides no protection at all.

Also, if a MK type disconnector did allow 1/4" of bolt travel before disconnecting, it would become badly peened by the impact from the bolt and start sticking down pretty quickly. If you find a MK pistol that allows more than 1/8" OOB, you really should replace the disconnector with one that's not so worn down.

Further, another error …. the hammer in a MK series pistol is an essential part for the disconnector. If the hammer is not secured by the sear, the gun will go full auto.
The hammer has no interaction with the disconnector. Only the trigger, sear, and bolt do. But I already agreed with your assertion about the sear and hammer notch needing to work together to not go full auto with my statement:

"Both types break the connection between trigger and sear until the trigger is released ==> semi-auto operation if the sear/hammer notch are mating up correctly".

As far as "disconnectors" of different types in pumps, levers and bolts, that may well be true. But my assertion of 2 basic types applies only to semi-auto actions - not to any and all repeaters. If there are more than 2 basic types for semi-autos, I'd like an example. I always enjoy learning and am willing to eat crow if my assertions can be proven wrong.

Have a blessed day!
 

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I understand that the disconnector on a pistol allows the pistol to fire only when the trigger is pulled, preventing a semi auto pistol from malfunctioning into automatic fire. (I hope I'm right on that). What I don't understand is how it does it - how it works? Can someone explain? Thanks
mjohnson1
In a 1911, the disconnector protrudes up from the receiver into a cutout in the bottom of the slide.
In this position the trigger is connected.

When the slide comes back, the bottom of the slide pushes the disconnector down,
disconnecting the trigger.
 

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Let's start at the beginning by describing a "sear". A sear requires at least two parts …. one with a "notch" of some sort and the other being a sharp edge that locks into the notch, often called a "sear". The most simple form of a sear would be a single action revolver with a sharp rear trigger extension that fits in a hammer notch to keep the hammer cocked. Once the trigger is pulled to the rear, the sear will release and allow the hammer to thrust forward. This operation is good for exactly one round fired. If you want to fire again, the sear must reset by first allowing the trigger to travel forward and reset then cocking the gun again. We don't normally think of SA or DA revolvers or any gun that is not a semi-auto as having a "disconnector" but in actuality, all guns are designed to have them in one form or another.

Keeping with the same concept of "one shot per trigger pull", semiauto rifles and pistols need a way to prevent the gun from going "full auto". The device that does this is a "disconnector", which simply means the sear is disconnected and reset each time the gun is fired.

Some examples …. a Ruger MK series pistol uses a "trigger bar" as a disconnector. It connects the trigger to the sear. Once the trigger is pulled, the trigger bar will pull the sear forward to release it from the notch in the hammer. The hammer will release and thrust forward causing the gun to fire. As the bolt moves to the rear from blowback, the bolt will cam the trigger bar down and push the hammer back. This will cause the hammer to cock again, however the trigger must be released to reset and make the gun ready to fire again. So …. the process has three functions: the sear is released to fire the gun. The disconnector is actuated to prevent the gun from firing again, and the trigger springs forward to reset and start the cycle again.

A 1911 type pistol also uses a hammer with a sear notch. The trigger is coupled to the sear via a trigger bow. There is also a physical part called a "disconnector" that prevents the sear from releasing the hammer unless the slide is fully forward where the top of the disconnector rod enters a cutout in the slide. If the disconnector is held down for any reason, the pistol will not fire. This design by John Browning does two things …. it prevents the pistol from firing unless the slide is fully forward (full battery) and it also prevents the gun from going full auto.

Striker fire pistols and rifles also have a disconnector of some sort, depending on design. All disconnectors, no matter what type of gun, have one single mission and that is "one trigger pull, one round fired". Releasing the trigger allows the disconnector to reset and once both are reset, the pistol is again ready to fire. Some striker fired pistols operate more like a DA revolver but it doesn't matter … the pistol will still have a disconnector to prevent it from going full auto.

Full auto rifles have an "auto sear" that prevents the gun from firing when out of battery, however an auto sear does not require the trigger to be released each time, thus full auto operation.

Iowegan,

Always thought on rifles such as the m16 the auto sear is more like a retarder of the hammer in other words in my theory it slows the hammer a bit to allow it not ride the bolt down when in full auto mode, allows proper force on the firing pin by the hammer, transfered to the primer. Just a thought I had rumbling around my mind I have never physically put my hands on.
 

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TestEngineer, A couple things …. if Ruger calls it a "magazine disconnect" and it prevents the gun from firing when there is no magazine in the gun ….. then it is a magazine disconnect, no matter how it actually works. You will note …. Ruger never called it a sear disconnect. I think you are getting a little hung up on semantics. The question is …. will the pistol fire when the magazine has been removed …. yes or no. If "no", it is a magazine disconnect.

Firing 1/10 inch out of battery will still blow the head off a case. Not part of the intended design but a favorable side affect that does help prevent firing out of battery. Yes, I have repaired many MK Series pistols that would fire when 1/4" or more out of battery and you are right …. the cam on the disconnector (trigger bar) had been peened down and needed to be replaced. As a temporary fix, filing the peened edge off the top of the disconnector bar will put the gun back in service. It takes thousands of rounds for this to happen but the fact is …. it does happen. Most owners don't have a clue because the gun still works as designed until the disconnector peening finally gags against the frame, causing malfunctions. The MK series basic design is very robust and forgiving but not quite perfect.

Most SA/DA pistols have a different disconnect design. Here's an example of a different type of disconnector …. a Ruger 22 LR SR22PB. It has a disconnector that disables the trigger after each round is fired rather than an actual sear disconnect. It works the same way when a magazine is not inserted …. the trigger does nothing but flop around. I'm sure there are more examples but I'd have to put on my thinking cap … and it is well worn.
 

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Tacky, No, an auto sear (ie: M-16) keeps the hammer fully cocked until the bolt goes into full battery. At that time, the auto sear will release the hammer (assuming the trigger is held back) and fire another round. If the hammer follows the bolt as you mentioned, it could result in an accidental discharge but it is not a positive method for full auto operation.

You may have heard terms like "fires from an open bolt" or "fires from a closed bolt". The old M-1927 Thompson sub-machine gun is an example of a fully auto gun that does not have an auto sear, rather it has a firing pin that stays extended until the trigger is released. In other words, it fires from an open bolt and uses straight blow back to cycle the action. Most other military full autos have an auto sear, much like a M-16 and fire from a "closed bolt" meaning the bolt actually locks in place until it is released by the op rod. All closed bolt full autos use an "auto sear" that trips when the bolt reaches full battery with the trigger pulled. Once the trigger is released, the sear will hold the hammer in the cocked position …. ready for the next trigger pull.

Interesting thread …. guns such as a pump action shotgun typically have a disconnector. If you hold the trigger back then operate the pump, the gun will only shoot once, until you release the trigger and pull it again. Older Winchester Mod 97s and Mod 12s did not have a disconnector so if you held the trigger back and pumped the action, as soon as the bolt locked up, the gun would fire again. The point is, nearly all modern repeaters …. rifles, shotguns or pistols have some sort of disconnector that enforce one trigger pull per shot. I can't think of any type that doesn't require a trigger reset but there are many different sear disconnector designs.
 

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I shouldn't have posted about the magazine disconnect; I read the OP's start of this thread thinking that might be the question at hand. Some good reading since then, I have also learned some more. Thanks.
 

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Discussion Starter #19
Great responses from everyone. Please let me ask a few specific questions to fine tune/confirm my understanding.
With the upper off I can see that when I pull the trigger with a cocked hammer, the sear moves forward and this allows the hammer to fall. I presume that the rear of the trigger bar is connected to the right side of the sear in some way (but I can't see it) . Is that correct?
Ignition occurs and the bolt is forced back. The bolt will pass over the back end of the trigger bar-is that when the "disconnect" occurs? Does "disconnect" mean that the trigger bar and sear are momentarily separated - disconnected?
When the bolt moves forward again and the trigger resets, the sear and trigger bar are connected again for the next shot?
When I hear the reset, what am I hearing? Thanks
 

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Here's a picture of a disconnector, hammer (&bushing), and sear that I made to show something else, but it may help here.



It shows the top of the sear looking from the front as it engages the hammer notch. The right side of the sear then, is on the left. The disconnector is rotated so the long arm is up instead of pointing out toward you as it would be in actual use. So the tab on the disconnector (red arrow) would actually be on the other side of the sear in practice.

When you pull the trigger, that tab would pull the sear out of the hammer notch to release the hammer. Then the bolt would cycle back, pushing the disconnector down and the tab would slip down into the notch you see at the bottom of the vertical line. That is the disconnect function. The sear spring would then push the sear back against the hammer and the tab would then be trapped in the sear notch. After the bolt has pushed the hammer back so the sear has caught it again, the bolt moves forward into battery with the next round. But even though the bolt is no longer holding the disconnector down, it stays down because the tab is still trapped in the notch.

When you release the trigger, the disconnector moves back (away from you in the picture) until the tab clears the front of the sear and gets lifted back into alignement with the solid portion of the sear. The click you hear is this reset function.

Hopefully this helps. Let us know if it still isn't clear.
 
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