What could cause a mechanical AD?

Discussion in 'General 1911 talk' started by BuckyP, Jan 27, 2019.

  1. BuckyP

    BuckyP Well-Known Member

    Sep 15, 2011
    With all these issues with striker fired guns firing without a trigger pull, it got me wonder:

    What would need to happen on a properly fitted 1911 to go off on its own, and what’s the likelihood?

    Assume cocked and locked. If the sear were to break enough, to clear the sear notch and half cock notch, could that do it?

  2. RatBikeRod

    RatBikeRod You Don’t Know Me!

    Nov 22, 2017


    CENTURIATOR Well-Known Member

    Dec 20, 2018
    It's hard to imagine a genuinely "accidental" discharge on a 1911, which would have intentionally had to be cocked and then something/somehow would cause the hammer to release. I've seen other weapons slam fire, but in any case, I think the root cause would be improper maintenance or simply neglect of adequate maintenance, including inspection of parts, regular maintenance of parts, etc. I'm looking forward however to hearing far more expert users of the 1911. With it's double safety system, it is hard to imagine a true "accidental" discharge - one caused by a mechanical malfunction.
    UBOATDOC likes this.
  4. BennyAdeline

    BennyAdeline Official Hi-Point Brand Representative

    Nov 26, 2018
    It would have to be a 1911 in very poor working order.

    The user would have had to let it get that way.

    BigJimP likes this.
  5. B81

    B81 Well-Known Member

    Aug 12, 2018
    In theory, a series 70 gun would fire if the sear were to catastrophically fail. That said, I thought @Jason Burton had done some tests along these lines and concluded that even a sear that had been damaged enough to slip past the hammer hooks would still provided enough resistance to prevent the hammer from striking the firing pin hard enough to ignite a round.
    BenchMonkey, FWoo45, BigJimP and 2 others like this.
  6. Greg3458

    Greg3458 Active Member

    Oct 31, 2018
    Dropping a series 70 1911 on the nose of the pistol.

    Sent from my iPhone using Tapatalk
  7. NPV

    NPV Well-Known Member

    Nov 15, 2017
    A sear pin installed backwards that fell out could also do it.
  8. dash

    dash Well-Known Member

    Apr 3, 2016
    I’ve tried to understand this before too. A smith can correct me if I’m wrong, a replacement thumb safety that’s poorly fit or doing a trigger job and then just dropping in the original thumb safety, without visually confirming that it’s still blocking the sear, could bring a mechanical discharge to a series 70. A trigger job including sear stoning will change the dimensional relationship of the sear and thumb safety slightly. That may be enough to allow the sear to eventually slip by the safety causing the hammer to fall. This is why it’s often suggested that a new thumb safety be fitted with a trigger job so the safety properly blocks the (potentially new location of the) sear. Some smiths can weld more material on the original safety and refit it.

  9. BuckyP

    BuckyP Well-Known Member

    Sep 15, 2011
    This is what I was hoping to hear. Hopefully some of our other resident smiths can confirm.

    If we're living in the real world, even the highest quality of parts could get by with a metallurgic defect or anomaly.
  10. BuckyP

    BuckyP Well-Known Member

    Sep 15, 2011
    My initial post was going to be more verbose to explain not including user or gunsmith negligence of incompetence.

    Another thing was going to try to rule out was semantics.
  11. BuckyP

    BuckyP Well-Known Member

    Sep 15, 2011
    Lightweight firing pins are suppose to prevent this, or so we're told.
  12. ZoidMeister

    ZoidMeister Consider my signature line before replying . . . .

    Dec 4, 2014

    You've got a better chance of hitting a lottery jackpot without actually buying a ticket . . . .

    Just my analysis.
  13. B81

    B81 Well-Known Member

    Aug 12, 2018
    Not to mention that dropping a 1911 nose first means that the round fires into the ground.
    FWoo45 and Kip like this.
  14. BBP

    BBP Enabler Sponsor

    Feb 1, 2014
    I installed a number of ambi safeties last year on my guns. They snick on and off, but I have no idea if they are poorly fit or not. Should I be concerned? Now I'm concerned.

    Sent from my SM-G950U using Tapatalk
    Steve Owens likes this.
  15. walleyemonster

    walleyemonster Well-Known Member

    Jan 11, 2017
    It is best to routinely do a function test of your pistol as to the grip safety and thumb safety. Pretty sure it has been discussed here before, so will not explain the process again. Maybe Steve Owens or one of our illustrious smiths will explain.
  16. dash

    dash Well-Known Member

    Apr 3, 2016
    If your gun passes the safety checks, then no you need not worry. There are a few inexperienced folks I’ve run across who have fit parts with little to no understanding of the 1911 or the effects. That’s how trouble could happen.

    I err to the side of caution when I’ve fitted thumb safeties (only done to my own guns). I’d ensure fit to the frame first with no ignition components installed. Then install the ignition components and fit the safety locking lug to the sear slowly for the tightest fit (blocking). I bought a 10-8 Performance armorer block to help file the correct angle. Doing this with the beaver tail safety removed provides a visual look at the engagement surfaces. Maybe I went overboard but this is the one area I was concerned the most about.

    I’d like to smith to weigh in on this and how much concern one should have when fitting their own thumb safety. @Steve Owens for input please.
    Last edited: Jan 27, 2019
    Steve Owens, Slapshot and BBP like this.
  17. BBP

    BBP Enabler Sponsor

    Feb 1, 2014
    I used the 10-8 block as well. I'll have to spend more time checking things over again when I have some time.

    Going to send you a message soon about something else.


    Sent from my SM-G950U using Tapatalk
  18. Integrity Arms

    Integrity Arms 1911 Pistol Smith

    Mar 20, 2017
    I think there should be a lot of concern as far as fitting a TS properly for several reasons. 1.) it is called a safety for a reason. It is the only part on the gun (Series 70) that is designed for the purpose of preventing an accidental pull of the trigger and discharging the firearm "accidentally, or negligently"
    Is there much concern for an improperly fit TS allowing enough movement of the sear to discharge the firearm? Anything is possible. Do parts break? obviously they do.. Poorly made parts are as bad if not worse than poorly fit parts. Having said that I have seen some very poorly fit TS on production guns, on guns the owner or someone else has tinkered with, but the part still functions and performs it's primary purpose of holding back the sear leg and preventing it from disengaging from the hammer.

    First of all anyone with the gumption or desire to change a TS should make themselves well acquainted with what the part is for, what it's purpose is, and how to properly fit it. I would never personally install a drop in TS. Just recently right here on the forum a member posted that he installed a new hammer on his pistol.. And now had hammer follow and with the thumb safety engaged could now discharge the firearm. Well that there should tell us how much the parts of a 1911 work together. How would a hammer cause a thumb safety to fail? It didn't.. The hammer changed the sear engagement angle and therefore rendered the TS useless. Nothing wrong with the TS..

    As far as fitting one. There is enough info on the internet, in books, and other gunsmiths websites that explain proper fitting for a TS. But, there are also some pretty shitty instructions as well. Dash I don't believe your explanation of fitting a TS was overboard at all, quite the contrary. Looking through the rear grip frame window with the BTGS removed is a very good way to see how the TS blocking lug is engaging or not engaging the sear leg.. Proper fitting requires this to just clear the sear leg, but also be filed to the correct angle. IMO you would have to go a great deal past this point to have an accidental or negligent discharge in some occasions, as I have seen some pretty poorly fit TS function and do there job. If all the ignition controls are properly fit as well.. And I said if the other ignition parts are fit properly. If you fit a TS and then change ignition part. It is wise to fit another TS.

    One more reason for concern and let's face it we are addicts, more than likely at some point in time somebody else is going to get that pistol.. Are they going to know what proper function and fit of the TS is? If the previous owner fit one improperly and just offed it on another person then imo they just put that person at risk. Not a good practice, I am sure nobody on this fine forum would do that to anyone.. But, we all know the saying **** happens. The A2 I have currently been working on had a TS and a trigger fit by the clients local gunshop smith. He asked me to check them out. I did, and I threw them out. Well, I am going to return them to the person with the gun. but it just goes to show you that sometimes even those that think they know what they are doing don't...

    I get it, I do.. I have been a diy guy my whole life. But, I will not do anything uninformed. I study, I read, I ask questions, I watch videos, read some more. etc.. and I have always went at everything I do "Especially with guns" with the understanding that someone else some day, some where is may have to depend on that pistol, that virtually what I have done could have repercussions even beyond my knowledge. I wouldn't want something unfortunate like that to be on my conscience. And I have my kids over, and neighbors, friends, my wife. Others shoot my guns. Something as important as a Safety cannot be left to chance imo..

    The original question was what would have to happen in a properly fit 1911 the sear would not break enough to clear the half cock notch. Something would have to break, or something be improperly fit. One of the test done on Cali guns is the drop test. A gun is dropped on it's nose and has to not discharge. So the answer to the original question is a catastrophic failure if all the parts were properly fit. A sear pin snaps, a hammer hook breaks off. etc... Parts can and do fail, but the 1911 has been considered safe in it proper fitting since it's inception in 1911. IF all parts are fitted properly the gun is by design not meant to fail.
    BBP, Chris O, rhjeepdriver and 3 others like this.
  19. Kip

    Kip Sir Kip Esquire

    Apr 12, 2016
    +1 Steve
    dash likes this.

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