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1911 Disconnector function check failure


brianj - now in Kansas

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So I decided to take the plunge: the 1911's hadn't been breeding in my gun safe quickly enough and so I decided to build one and help them along (once, I'm done, I'll post a thread on how things went). The brief version is that the firearm is built, completed, and is happy.

 

Except...

 

The standard function check that I was taught back in my Army days goes as follows:

 

1: Clear the weapon.

2: With the weapon clear and hammer down, pull the hammer completely to the rear or rack the slide and engage the thumb safety. Attempt to pull the trigger. The hammer will not fall.

3: Disengage the thumb safety and take an abnormal grip. The hammer will not fall.

4: With the thumb safety disengaged, take a normal grip on the the weapon and pull the trigger. The hammer WILL fall.

5: With the trigger pulled to the rear, pull the slide to the rear and release. The hammer will not fall. Release the trigger. There will be an audible reset. Pull the trigger, the hammer will fall.

6: Pull the hammer back to half rooster (See what I did there, Valinda? :) ) and pull the trigger with a normal grip. The hammer will not fall. (I know, unless you have a series 80).

 

The weapon passes all of these tests.

 

7: Pull the hammer back to full rooster. Push back on the front of the barrel and slide to engage the disconnector. The hammer will not fall.

 

HERE'S where the problem happens.

 

When I fully rooster the hammer and push back on the front of the slide and barrel, the hammer will fall if I pull the trigger. All contact faces on the sear and disconnector have been polished except for the sear point of contact with the hammer: as to why I didn't stone the sear where it contacts the hammer, I'll talk about that when I do the full post on the build process. At this point, everything feels smooth and free of grit.

 

So, are there any thoughts out there as to likely culprits or hints on things I should check?

 

Thanks,

 

Brian

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Are you doing the right function test?

I don't know 1911s at all... what a complicated beast compared to JMB's better battle pistol!

 

I looked at this video and it matches things I've read at the 1911 Forum/1911 Addicts.

 

As a High Power fan, I'm following to see what I can learn from this.

 

I actually have a Hi-Power on my "One of these days..." shopping list. I'll confess that this particular 1911 isn't completely milspec. First, it's a CCO, instead of a full 5". Second, this 1911 is Para-ramped, so it's got the same barrel style as a Hi-Power. I've had issues with JHP's feeding in a couple of my other regular 1911s, and when this parts supplier offered a ramped frame and barrel for $30 extra, I grabbed it.

 

Bri

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How far back are you pushing the slide? Sometimes to decrease felt working moment to overcome the disconnector slot, the disconnector engagement slot in the slide gets ramped. If the ramp is too deep, large, or otherwise done improperly, the disconnector can still find enough room to...well...not disconnect. For grins, I’d pull the slide and see what the disconnector slot looks like. Just my $.02
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Are you doing the right function test?

I don't know 1911s at all... what a complicated beast compared to JMB's better battle pistol!

 

I looked at this video and it matches things I've read at the 1911 Forum/1911 Addicts.

 

As a High Power fan, I'm following to see what I can learn from this.

 

I actually have a Hi-Power on my "One of these days..." shopping list. I'll confess that this particular 1911 isn't completely milspec. First, it's a CCO, instead of a full 5". Second, this 1911 is Para-ramped, so it's got the same barrel style as a Hi-Power. I've had issues with JHP's feeding in a couple of my other regular 1911s, and when this parts supplier offered a ramped frame and barrel for $30 extra, I grabbed it.

 

Bri

 

The Tisas BR9, a High Power clone from Turkey, is actually pretty nice. I bought the Stainless Steel version last March... added SFS and a C&S Wide Combat Trigger. Had to replace a broken extractor after 361 rounds but I had a spare on hand.

 

I'm now waiting for a new trigger assembly to be available from BH Spring Solutions. They say it rivals the 1911 trigger and the magazine disconnect no longer interferes with the trigger pull. It can still be removed.

 

One of these days I will play with 1911s.

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How far back are you pushing the slide? Sometimes to decrease felt working moment to overcome the disconnector slot, the disconnector engagement slot in the slide gets ramped. If the ramp is too deep, large, or otherwise done improperly, the disconnector can still find enough room to...well...not disconnect. For grins, I’d pull the slide and see what the disconnector slot looks like. Just my $.02

 

The Army said to push back on the barrel and slide until they stopped. On this firearm, that comes out to around 0.24". The disconnector engagement slot is about 0.45" long. When doing some measurements, I'd almost thought I'd run up against a smoking gun (so to speak) the disconnector engagement slot is a LOT closer to the back of the slide than the slot on one of my others. For the firearm under construction, it's measuring 0.046" from the back end of the slot to the back of the slide (not counting the firing pin stop). I have another officer's model where the back of the disconnector engagement slot is 0.072" from the back of the slide. And then I measured that same distance on my 1911R1, and it came out to 0.045". And all of the other ones pass the disconnector function check.

 

One other thing I'm going to check as long as everyone's out of the safe is the height of the disconnector. I'm wondering if this one isn't protruding far enough.

 

Brian

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If you pull the grip safety out, you can work the slide and then watch what the disco is doing from the grip safety channel while you work the slide. You should be able to see if it is being pushed down and interfacing the sear legs or not.

It also is not outside the realm of possibility that you got a runt disco and the poor little guy is just too short. Or your sear pin holes could be off. Just some thought. I’m not a gunsmith, but I have built several 1911’s and 2011’s from frame up. I’m just trying to run through my head the possibilities.

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If you pull the grip safety out, you can work the slide and then watch what the disco is doing from the grip safety channel while you work the slide. You should be able to see if it is being pushed down and interfacing the sear legs or not. It also is not outside the realm of possibility that you got a runt disco and the poor little guy is just too short. Or your sear pin holes could be off. Just some thought. I’m not a gunsmith, but I have built several 1911’s and 2011’s from frame up. I’m just trying to run through my head the possibilities.

 

This is the direction I'm starting to lean, as well. Fortunately, I have several other 1911s who have all volunteered to be dissected tomorrow morning so I can compare both the full OAL and the distance from the pin-hole to the top of the disconnector with known good items. I'll also probably try to swap out a known good disconnector to see if it makes any difference.

 

Bri

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Let me know what you find out. If a known good disco does not work I can only think of three possibilities.

1. Disco notch in the slide out of spec

2. Sear pin holes out of spec

3. Sear legs out of spec

 

I cannot remember...have you installed the suspect disco into a known working unit? This would check the disco itself against all three of the above that are known good and take take them out of the equation. If it works in a known good 1911 then it would point to one of those three. If it doesn’t work in a known good gun then it probably is the disco itself. Good luck!

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Well, folks, it looks like stacked tolerances were the issue (note to self: "Self, I think the time has come to get that fancy set of $100 digital calipers on Amazon instead of the $30 pair from Home Despot." I trust the Home Depot calipers down to about .003" or so. After that, it gets hard to reproduce the measurement.)

 

While remembering that this game is a game of hundredths (if not thousandths) of an inch, I pulled out my Ruger Commander, and took some very interesting measurements. First I measured from the deck down to the top of the sear hole on the right and left sides of both my Ruger and my homemade:

 

Ruger

Left : 0.6395"

Right: 0.6467" <- This was a Whisky Tango Foxtrot moment, let me tell you!! I actually triple-checked, and it came out the same way each time.

 

Homemade

Left : 0.6495"

Right: 0.6480"

 

So, theoretically, my holes on my homemeade firearm are actually straighter than the commercial firearm. I'm shocked, stunned, and appalled.

 

Then, the OALs of the disconnectors:

Ruger: 1.3000" even

Homemade: 1.3050"

 

So, we're talking 50 thousandths, which might be suggestive. But wait, there's more. Next was the distance from the top of the disconnector to the top of the sear pin loop in the middle.

Ruger: 0.6535"

Homemade: 0.6495"

 

So, we can see that the sear that came with my kit is about 4 thousandths of an inch shorter in the critical dimension, going in a firearm where the hole is at least 1 thousandth of an inch longer. So, I swapped disconnectors, and BOTH firearms passed all function tests after the swap.

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Well, folks, it looks like stacked tolerances were the issue (note to self: "Self, I think the time has come to get that fancy set of $100 digital calipers on Amazon instead of the $30 pair from Home Despot." I trust the Home Depot calipers down to about .003" or so. After that, it gets hard to reproduce the measurement.)

 

While remembering that this game is a game of hundredths (if not thousandths) of an inch, I pulled out my Ruger Commander, and took some very interesting measurements. First I measured from the deck down to the top of the sear hole on the right and left sides of both my Ruger and my homemade:

 

Ruger

Left : 0.6395"

Right: 0.6467" <- This was a Whisky Tango Foxtrot moment, let me tell you!! I actually triple-checked, and it came out the same way each time.

 

Homemade

Left : 0.6495"

Right: 0.6480"

 

So, theoretically, my holes on my homemeade firearm are actually straighter than the commercial firearm. I'm shocked, stunned, and appalled.

 

Then, the OALs of the disconnectors:

Ruger: 1.3000" even

Homemade: 1.3050"

 

So, we're talking 50 thousandths, which might be suggestive. But wait, there's more. Next was the distance from the top of the disconnector to the top of the sear pin loop in the middle.

Ruger: 0.6535"

Homemade: 0.6495"

 

So, we can see that the sear that came with my kit is about 4 thousandths of an inch shorter in the critical dimension, going in a firearm where the hole is at least 1 thousandth of an inch longer. So, I swapped disconnectors, and BOTH firearms passed all function tests after the swap.

 

Don’t write posts like this before coffee. I can see at least one decimal point I dropped. I’m edumacated. Honest.

 

 

Sent from my iPhone using Tapatalk

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