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Rimcrew

1911 Fires When Thumb Safety Engaged

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I have recently had two brand new 1911's fire when I engaged the thumb safety.   Not disengaged, but engaged.  I finished a string, applied upward pressure to the thumb safety, and the gun discharged.

 

During both episodes, my finger was alongside the slide, not even the frame, so I know I did not touch the trigger when engaging the safety.  Since I know someone will claim I did, I have been shooting competitively for a decade, and have never had this happen until these two guns (same manufacturer).  I shoot one to three matches a week, and have never been DQ'd for an AD, and I don't recall ever even receiving a warning for finger, so.....

 

What could be causing this issue?  I don't want to travel to a major match and have my gun discharge when I am engaging the safety, that would be costly, not to mention VERY unsafe.  I sent the first one back to the builder, and he blamed me.  Surprise, surprise.  So now I am hoping to get some unbiased information on possible causes before I remove all the fire control components and replace them.  I know I can fix it this way, but I really want to understand what is happening before I just throw in the towel and replace parts.

 

Thanks for any guidance you can provide.

 

Edited by Rimcrew

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1) make sure your gun is UNLOADED

2) attempt to make the gun drop the hammer again, try everything.

3) insert empty mag, redo steps 1 & 2

4) repeat

5) if the hammer drops then you have identified the problem is not YOU.

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The thumb safety should block the sear.  For it to fire upon engaging the safety, it sounds as if the thumb safety ius bumping the sear instead of blocking it.

 

What is your trigger pull weight?  There may be some sear spring adjustment to have more pressure aghainst the seat and disconnector may help.

 

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1 hour ago, Guy Neill said:

The thumb safety should block the sear.  For it to fire upon engaging the safety, it sounds as if the thumb safety ius bumping the sear instead of blocking it.

 

What is your trigger pull weight?  There may be some sear spring adjustment to have more pressure aghainst the seat and disconnector may help.

 

 

Thumb safety also blocks the hammer. Engaged, even if the sear was tripped it would still not allow the hammer to fall. Something is not fitted right that is for sure, but I cannot see a way for the thumb safety to hit anything to cause the gun to fire. Is it a series 80?

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27 minutes ago, Dranoel said:

 

Thumb safety also blocks the hammer. Engaged, even if the sear was tripped it would still not allow the hammer to fall. Something is not fitted right that is for sure, but I cannot see a way for the thumb safety to hit anything to cause the gun to fire. Is it a series 80?

Just curious: how does the thumb safety block the hammer? (other than blocking the sear, of course)

 

ThumbSafety.jpg

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Having looked it over very well, and just speculating at the moment....  What if the thumb safety (part A above), were to contact the sear (part B ) during activation.  Could A catch on the corner of B and lift it enough to fire the gun? 

 

Having loosely assembled mine and tested various ways of making the sear fall while activating the safety, this is the only thing that I can see that would make sense.  

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2 hours ago, Guy Neill said:

The thumb safety should block the sear.  For it to fire upon engaging the safety, it sounds as if the thumb safety ius bumping the sear instead of blocking it.

 

I think you are correct.  This is the only 1911 I have ever seen where they fit the sear to the thumb safety.  There are very close together and I think the edges may be catching and lifting the sear.  I'm thinking a very small radius at the edge of each part may solve the problem.

 

The trigger is around 2.5 lbs, so not particularly light.  

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2 hours ago, ChuckS said:

Just curious: how does the thumb safety block the hammer? (other than blocking the sear, of course)

 

ThumbSafety.jpg

 

In your illustration if you look at the orange section directly above red section "A", You will notice that it nests inside the concave cut of the hammer when the safety is engaged.

 

One way to test this is to cock the hammer, then while holding the hammer, trip the sear and let the hammer fall just a hair. Just enough that the sear cannot re-engage. Now thumb the safety up. It won't go all the way as the sear being disengaged will block it but it will go far enough to hold the hammer as long as you hold the safety in place. let go of the hammer and you can hold it in place with the thumb safety and even reset the sear by forcing the safety up, which pushes the hammer back and allows the sear to re-engage. Or thumb the safety down and the hammer will fall to half cock.

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2 hours ago, Rimcrew said:

Having looked it over very well, and just speculating at the moment....  What if the thumb safety (part A above), were to contact the sear (part B ) during activation.  Could A catch on the corner of B and lift it enough to fire the gun? 

 

Having loosely assembled mine and tested various ways of making the sear fall while activating the safety, this is the only thing that I can see that would make sense.  

 

The spur on the thumb safety that blocks the sear moves in the direction of that arrow as it engages. The contact lug on the sear must move in the direction of it's own arrow in order to disengage the hammer hook. This is how the safety blocks the sear. Engaging the safety should, if anything, force the sear into better engagement of the hammer hook.

 

Granted that is with a properly fitted safety. If the safety was cut at a weird angle and long, theoretically it might catch the lug on the sear in such a way as to pull it instead of pushing it. But even my twisted mind can't see how that would be possible with standard parts.

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I was wondering about that also. The only way I can see is that the top edge of the safety stub is catching on the bottom edge of the sear and pulling it rearward. In any case, if these were my 2 new 1911's, they would be on a trip back to the builder. ?

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Actually, I may have an answer.... 

 

In looking at the illustration I was thinking of the way the actual contact areas interact and wasn't taking into account the area of the thumb safety spur that is filed down to fit it. That spur runs all the way out to the side plate on the outside of the frame. Most smiths, when filing down the tip of the spur don't remove metal all the way to the side plate. In most cases it doesn't matter because that is inside the hole in the frame where the spur goes through. However if there was enough of a burr left out there that contacted the side of the sear, it might be possible for it to have a pulling effect on the sear at the initial movement of the safety. If the smith also filed down the hammer hooks to get a shorter sear engagement, the combination might just cause what you are experiencing.

 

Any of that make any sense?

 

Edited by Dranoel

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i'd send both back to the builder asap.  you mess with them at all and then anything else wrong with these will be construed as being your fault.  not having the gun fire when applying the safety or having it engaged is pretty basic stuff.

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On 8/21/2018 at 2:02 AM, Rimcrew said:

Having looked it over very well, and just speculating at the moment....  What if the thumb safety (part A above), were to contact the sear (part B ) during activation.  Could A catch on the corner of B and lift it enough to fire the gun? 

 

Having loosely assembled mine and tested various ways of making the sear fall while activating the safety, this is the only thing that I can see that would make sense.  

correct. 

A corner start position is under B corner before engaging the safety

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Interesting problem.  Did the ADs occur while the magazine was in the gun, or had you removed the mag in preparation to show clear?

Just wondering if the disconnector finger of the sear spring was touching the mag and preventing full engagement of the disconnector.

Also, how much pretravel was set in the new trigger?  Are the new triggers free to travel in their "window" in the frame.

Last, are you a lefty?  That's bad luck anyway.  :^)

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A correctly fit 1911/2011 Thumb Safety in no way 'blocks' the hammer.  Change my mind. 

Edited by scubajosh77

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Can you get the problem to repeat on the bench?   If so remove the grip safety .   That gives you a nice window to watch the 

workings of the trigger/sear/hammer/thumb safety.    

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5 hours ago, scubajosh77 said:

A correctly fit 1911/2011 Thumb Safety in no way 'blocks' the hammer.  Change my mind. 

 

I did three weeks ago. Go halfway up the page and you'll see it.

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10 minutes ago, Dranoel said:

 

I did three weeks ago. Go halfway up the page and you'll see it.

The orange area you refer to is flat,  rests outside of the frame, and has no contact with the hammer.  Still waiting.................

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3 minutes ago, scubajosh77 said:

The orange area you refer to is flat,  rests outside of the frame, and has no contact with the hammer.  Still waiting.................

 

Hope you're not holding your breath. I explained it once and even explained how to test it. You don't believe me? Then don't. No skin off my arse. And I won't hold my breath waiting for an apology when you figure it out.

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