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  #1  
Old 01-15-2011, 12:17 AM
Control Control is offline
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1911 Trigger Over-travel and Hammer/Sear Engagement




Hi. I have a simple question regarding how the over-travel screw affects the hammer half cock notch and sear engagement.

I've read that when setting the over-ravel screw one must set the screw such that when the trigger is fully to the rear the hammer hooks fully clear the half cock notch. However, when I did this on my 1911 the overtravel was a bit too much in my opinion.

My hammer is an Ed Brown Hardcore, and the half cock notch is shaped such that it only touches the middle part of the sear and not the left and right parts of the sear where the hammer full cock hooks engage.

A picture of the Ed Brown hammer can be seen on their website.

http://edbrown.com/cgi/htmlos.cgi/00...05016920278603

Note the point made next to the hammer on the page: "Narrowed half-cock notch eliminates sear damage."

For this type of hammer, I cannot see how the sear rubbing the half cock notch on the hammer is a big concern given that the full cock hooks do not touch the same part of the sear.

I'm tempted to leave the overtravel screw in a state where the sear does brush up against the half cock notch in order to minimize my over-travel. Does anyone have any opinions or experience with this type of setup?

Thanks!
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  #2  
Old 01-15-2011, 12:51 AM
Maglin Maglin is offline
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Doesn't sound like a good idea. Might cause your sear to bounce and not engage the full cock notch. I'm sure someone more knowledgeable will give you a definitive answer. Just thinking how the sear/disconnecter works it seems like allowing the sear to ride or come in contact with the hammer during the firing cycle is asking for trouble.
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  #3  
Old 01-15-2011, 02:31 AM
Magnumite Magnumite is offline
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The overtravel needed is determined by the difference between the radius of the hammer pin/hammer hooks and the hammer pin/half cock notch radius. The overtravel you are feeling isn't that significant if it is adjusted properly, as you stated you had. If you have ever seen a sear beaten by the half cock notch from insufficient over travel, I think you would change your mind.
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  #4  
Old 01-15-2011, 07:43 AM
BigJon BigJon is offline
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As usual, Mag's sterrin' us in the right direction, Control. Think about what a tiny area of the sear nose is holding the hooks. If the half-cock notch is snicking the sear nose every time the gun cycles, might it be possible to eventually chip it? And if it does, could the chip go outward enough to compromise the tiny areas that have to hold the hooks? Sure doesn't sound like an acceptable risk to me, especially since the increase in OT you'd need to go from where you are tothe point that the grazing is eliminated is so incredibly tiny.
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Last edited by BigJon; 01-15-2011 at 08:12 AM.
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  #5  
Old 01-15-2011, 09:39 AM
log man log man is offline
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Wrong!!

LOG
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  #6  
Old 01-15-2011, 10:43 AM
orfeo orfeo is offline
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Quote:
Originally Posted by log man View Post
Wrong!!

LOG
Sitting here eagerly awaiting the followup that I'm sure must be coming. . .

(Log never leaves ya hangin' for long, far as I've ever noticed)
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  #7  
Old 01-15-2011, 10:55 AM
log man log man is offline
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Originally Posted by orfeo View Post
Sitting here eagerly awaiting the followup that I'm sure must be coming. . .

(Log never leaves ya hangin' for long, far as I've ever noticed)
The answers the OP got were correct, and I just wanted to add to that.

The half cock notch catching as it passes the sear nose should not be tolerated. This will eventually damage the sear and if it catches stop the action, not good. Re-set will also be so short that bump fire with a relaxed trigger finger will also occur with a light trigger. The idea of tuning is to perfect function, not abuse it.

LOG
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  #8  
Old 01-15-2011, 11:10 AM
Quack Quack is offline
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Quote:
Originally Posted by log man View Post
Wrong!!

LOG
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  #9  
Old 01-15-2011, 11:23 AM
BigJon BigJon is offline
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Quote:
Originally Posted by log man View Post
The answers the OP got were correct, and I just wanted to add to that.
Only you would get up early and reach all the way across the country just to pick on your friends.

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Originally Posted by log man View Post
The half cock notch catching as it passes the sear nose should not be tolerated. This will eventually damage the sear and if it catches stop the action, not good. Re-set will also be so short that bump fire with a relaxed trigger finger will also occur with a light trigger. The idea of tuning is to perfect function, not abuse it.
You know, it occurs to me that the amount of room available for the firing mechanism to work (the position of trigger stirrup when at rest, to its position at the end of OT) is like a tall pile of snow - one can only push the edges towards each other so far before things start falling apart.
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Last edited by BigJon; 01-15-2011 at 11:26 AM.
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  #10  
Old 01-15-2011, 12:15 PM
Jammer Six Jammer Six is offline
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The link you gave goes to some video.
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  #11  
Old 01-15-2011, 12:28 PM
log man log man is offline
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Originally Posted by Jammer Six View Post
The link you gave goes to some video.
That's just the home page of EB, go to parts. Here's the hammer in SS or CS.



LOG
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  #12  
Old 01-15-2011, 01:56 PM
Dave Waits Dave Waits is offline
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Gentlemen, I thought the way to set overtravel was to turn the trigger-screw in until the hammer wouldn't drop, turn back out til it did, then another half-turn. Now I read all this, did I get wrong information? Or, is the Ed Brown hammer that different?
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  #13  
Old 01-15-2011, 02:11 PM
Quack Quack is offline
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Quote:
Originally Posted by Dave Waits View Post
Gentlemen, I thought the way to set overtravel was to turn the trigger-screw in until the hammer wouldn't drop, turn back out til it did, then another half-turn. Now I read all this, did I get wrong information? Or, is the Ed Brown hammer that different?
that's mostly correct, the 1/2 turn is sort of a ball park number. i slowly thumb the hammer down (with the hammer strut out of the MSH) and adjust the over-travel until i feel the hammer just clearing the 1/2 cock notch, then i give it a little more clearance from there.
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  #14  
Old 01-15-2011, 02:58 PM
log man log man is offline
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The way I like to adjust the over travel screw leaves no doubt. Remove the GS and MSH and flip the strut up out of the way, slip the MSH back in to hold sear spring. Now adjust the screw in until the trigger can't release the hammer, back it out until you can, now swing the hammer and feel for interference , back it out until you can no longer feel a rub when the trigger is held back, and the half cock notch doesn't rub as well. There, that's as close as it should be, and a 1/2 to 1 full turn out will be a good place to leave it. Now put a drop of Loctite #290 on the screw and forget about it. Leaving the screw very close to interference is okay, but the reset will be very short and if the trigger is light you may experience bump firing.

LOG
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  #15  
Old 01-15-2011, 03:51 PM
Control Control is offline
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It's interesting that Ed Brown would design the part such that the half cock notch is cut down to minimize sear damage in the case of sear/half cock notch contact if he didn't intend to allow any rubbing there.

I do wonder if he ships his pistols with the over-travel screw set back far enough to enable sear/half cock notch rubbing. I don't have a NIB Ed Brown to test but that might be interesting to check out.

For now, I think I'm going to dress down the front of the the half cock notch on my hammer such that I can set the overtravel screw where I want it. Hopefully there is enough material on the front of the half cock notch that there is some to spare.

Log man: That's how I set the over-travel as well. It's far easier to feel for the half cock notch rub on the sear without the mainspring pushing the hammer!
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  #16  
Old 01-15-2011, 04:07 PM
log man log man is offline
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I'm sure Ed Brown does not allow any rub, rub spells trouble. Most hammer's half cock require just a bit more over travel than the full cock, also more engagement. Why do you wish for so little over travel? The damage occurs with the full width half cock after a fall to half cock, and can mar the engagement surface, so the reduced to center keeps the half cock contact separate from the full cock hammer hook contact. But be assured that a few hard drops to a reduced half cock isn't a good thing.

LOG
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Last edited by log man; 01-15-2011 at 04:13 PM.
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  #17  
Old 01-15-2011, 06:27 PM
BBBBill BBBBill is offline
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Quote:
Originally Posted by Control View Post
It's interesting that Ed Brown would design the part such that the half cock notch is cut down to minimize sear damage in the case of sear/half cock notch contact if he didn't intend to allow any rubbing there.
That design did not originate with Ed Brown. The Colt Gold Cup has had that design since day one and others did that well before Ed adopted it to his production pieces. It was never intended to allow rubbing. Its sole function is to remove the possibility of damage to the actual engagement area of the sear face in the event of inadvertent contact in a fall to half cock.

Quote:
Originally Posted by Control View Post
I do wonder if he ships his pistols with the over-travel screw set back far enough to enable sear/half cock notch rubbing...
If one were shipped from his shop set that way, it was purely an oversight.

Quote:
Originally Posted by Control View Post
For now, I think I'm going to dress down the front of the the half cock notch on my hammer such that I can set the overtravel screw where I want it. Hopefully there is enough material on the front of the half cock notch that there is some to spare...
Don't do that. You will regret it.

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I'm sure Ed Brown does not allow any rub, rub spells trouble... But be assured that a few hard drops to a reduced half cock isn't a good thing.

LOG
+1 I've seen half cocks shear from that.
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  #18  
Old 01-15-2011, 07:09 PM
Gary300 Gary300 is offline
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Quote:
Originally Posted by log man View Post
The way I like to adjust the over travel screw leaves no doubt. Remove the GS and MSH and flip the strut up out of the way, slip the MSH back in to hold sear spring. Now adjust the screw in until the trigger can't release the hammer, back it out until you can, now swing the hammer and feel for interference , back it out until you can no longer feel a rub when the trigger is held back, and the half cock notch doesn't rub as well. There, that's as close as it should be, and a 1/2 to 1 full turn out will be a good place to leave it. Now put a drop of Loctite #290 on the screw and forget about it. Leaving the screw very close to interference is okay, but the reset will be very short and if the trigger is light you may experience bump firing.

LOG
I am about to install a Ed Brown Ultralight trigger into my Norinco and will follow your advice about adjusting the over travel set screw. The thing is, how do you apply the locktite to the screw threads if the screw is already installed in the the threads of the trigger shoe and have it securley lock the threads?

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Old 01-15-2011, 07:13 PM
log man log man is offline
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Originally Posted by Gary300 View Post
I am about to install a Ed Brown Ultralight trigger into my Norinco and will follow your advice about adjusting the over travel set screw. The thing is, how do you apply the locktite to the screw threads if the screw is already installed in the the threads of the trigger shoe and have it securley lock the threads?

Pick up a bottle of Loctite #290 which is a wicking formula. You can carefully place a drop with a scribe or toothpick in the front of the hole and it will wick in and lock.

LOG
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Old 01-15-2011, 07:18 PM
quickstop quickstop is offline
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Quote:
Originally Posted by Gary300 View Post
I am about to install a Ed Brown Ultralight trigger into my Norinco and will follow your advice about adjusting the over travel set screw. The thing is, how do you apply the locktite to the screw threads if the screw is already installed in the the threads of the trigger shoe and have it securley lock the threads?

from mfg. website
octite® Threadlocker Green 290™ is designed for the locking and sealing of threaded fasteners. Due to it's low viscosity and capillary action, the product wicks between engaged threads and eliminates the need to disassemble prior to application. Loctite® Threadlocker Green 290™ cures when confined in the absence of air between close fitting metal surfaces. It prevents loosening from shock and vibration and leakage from shock and vibration and protects threads from rust and corrosion. The product can also be used to fill porosity in welds, casting and powder metal parts. Localized heating and hand tools are needed for disassembly.
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  #21  
Old 01-16-2011, 12:28 AM
Gary300 Gary300 is offline
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Originally Posted by log man View Post
Pick up a bottle of Loctite #290 which is a wicking formula. You can carefully place a drop with a scribe or toothpick in the front of the hole and it will wick in and lock.

LOG
Thanks, just ordered some from McMaster.
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  #22  
Old 01-16-2011, 12:53 AM
Control Control is offline
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Thanks again for all of the advice.

Quote:
Control:
For now, I think I'm going to dress down the front of the the half cock notch on my hammer such that I can set the overtravel screw where I want it. Hopefully there is enough material on the front of the half cock notch that there is some to spare...
Quote:
BBBill:
Don't do that. You will regret it.
Dressing the outer side of the half cock notch is mentioned in Jerry Kuhnhausen's 1911 Shop Manual, Volume 2. On page 174 it states: If the sear lightly brushes the outer surface of the hammer, at or above the safety notch, adjust the trigger screw to permit fractionally greater sear rotation. If contact is greater, remove the hammer and clearance the outer front surface above the safety notch with a medium Eze-lap diamond hone. Then reinstall the hammer, readjust, and recheck.

I think I'm going to take Mr. Kuhnhausen's advice and dress down the hammer (I've handled more than a few 1911's and this one's over-travel is fairly excessive). I'll start with some dykum and continuously check along the way to make sure I don't remove too much.
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  #23  
Old 01-16-2011, 08:07 AM
Magnumite Magnumite is offline
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There are some problems with vague descriptors such as slightly and greater. Where does slightly stop and greater begin?

My take on the half cock notch being of greater radius than the hooks was too negate sear inertia. Think about it, you have the trigger back as far as it goes upon firing. You get hammer follow for whatever cause. The hammer hooks slip past the sear. The hammer is pushed by the hammer spring with 23, 19 or whatever force and is moving. The sear does have some inertia, is it greater than the sear spring can overcome in that moment of time, dunno, but with only 1 - 2 pounds of force on it, it is not near as much as the hammer has on it. So maybe it is possible for the hammer halfcock notch to pass the sear since it is the same or perhaps less radius than the hook radius before the sear spring can overcome that inertia.

This is a theory, I haven't built one and tested it. I have seen halfcock notches with their radius reduced as such and they look scary thin. I also understand factors such as the hammer is greater mass than the sear, it has a greater moment arm on it, what is the ratio of inertia/spring force ratio of the sear compared to that of the hammer, etc.

Simpler approach is to call or email Ed Brown and ask what the amount of additional overtravel (radius) should be and go from there. Then ask him why he still builds his hammers as he does.
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Last edited by Magnumite; 01-16-2011 at 08:13 AM.
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  #24  
Old 01-16-2011, 10:24 AM
BigJon BigJon is offline
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Best o' luck.
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Last edited by BigJon; 01-16-2011 at 11:25 AM.
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  #25  
Old 01-16-2011, 10:37 AM
CWarner CWarner is offline
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Quote:
Originally Posted by Control View Post
Thanks again for all of the advice.




Dressing the outer side of the half cock notch is mentioned in Jerry Kuhnhausen's 1911 Shop Manual, Volume 2. On page 174 it states: If the sear lightly brushes the outer surface of the hammer, at or above the safety notch, adjust the trigger screw to permit fractionally greater sear rotation. If contact is greater, remove the hammer and clearance the outer front surface above the safety notch with a medium Eze-lap diamond hone. Then reinstall the hammer, readjust, and recheck.

I think I'm going to take Mr. Kuhnhausen's advice and dress down the hammer (I've handled more than a few 1911's and this one's over-travel is fairly excessive). I'll start with some dykum and continuously check along the way to make sure I don't remove too much.

I would check your sear length before doing anything else.

The original halfcock is designed so that it will catch a broken sear.

Im getting conflicting thoughts based on what you've presented here.

Excess overtravel and half cock bumping? Hmm

Ive handled a few 1911's too, and anxiously await the results you get.

CW
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