1911 trigger slap


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mister2
March 24, 2012, 02:50 AM
I've searched this site and other sites for any info on the topic to no avail. Most posters who bring it up are told their finger is either getting pinched between trigger & trigger guard, or is abraided by serrations on the trigger face.

My experience is nothing like the above. I can actually feel the familiar sting on my finger when I pull the trigger on my Norinco. And by "familiar" I mean SAR-1 trigger slap.

Here's what I think: First of all, my trigger has a heavy return, even before the sear comes into play. But the trigger has no return spring of its own and rests against the disconnector which does have the middle leaf of the sear spring on it. When I dry fire, there is absolutely no slap. But when I fire a live round, what I think happens is that as the slide moves back, it plunges the disconnector downward, wedging deeper between the trigger and the spring. This of course instantly increases the spring pressure on the trigger, driving it forward. Compress this action within the fraction of a second and it will feel like a slap.

I've considered recoil, as in the case of rounds being pressed against the forward wall of the magazines when the frame moves backward, but the trigger simply has not enough mass to slap the way I feel it.

I'll take a look at this tomorrow.

Thoughts?

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1911Tuner
March 24, 2012, 06:59 AM
But when I fire a live round, what I think happens is that as the slide moves back, it plunges the disconnector downward, wedging deeper between the trigger and the spring. This of course instantly increases the spring pressure on the trigger, driving it forward.

Tryin' to wrap my head around this, but the disconnect overlaps with the sear leg a very small amount. When it moves down via the slide, it's only wedged under spring tension until it moves below the sear leg. At that point, the disconnect is out of play, and the trigger is only under whatever tension the sear spring can impose...maybe two pounds.

mister2
March 24, 2012, 10:06 AM
Tuner, thanks for your response.

The middle leaf of the sear spring never leaves the disconnect as it travels up and down depending upon where the slide is, does it? This is critical to my reasoning. Now, when the slide drives the disconnect down, the wedge end of the disconnector goes deeper between the trigger and the spring. For discussion purposes, let's assume the spring heavy enough to be momentarily immovable. The full wedging action of the disconnect then displaces the trigger an equal amount, since the spring does not move. Speed this sequence up by the acceleration of the cutout ramp in the slide and the only object that absorbs this impulse is the trigger finger. In reality, of course, the spring does move back, just as the trigger moves forward. I suspect very little actual displacement is need to feel the "slap" which is more like a "sting".

Looking at the various animations of 1911 sear and hammer action, the trigger never moves forward as the disconnect slides down to release the sear, but I submit it actually does, even in tiny amounts.

FWIW, the "slap" feels worse when I deliberately keep pressure on the trigger through the firing sequence.


OR.....is it possible that as the trigger/disconnector assembly moves the sear back to release the trigger, the disconnector hole runs out of clearance and contacts the sear pin in such as way that it transmits a forward impulse to the trigger? In a sense this seems more plausible than the "heavy spring" scenario because there certainly are 1911s out there with no trigger slap and sear spring rates (at least on every 1911 I've tried) fall within a reasonably narrow range.

I'll get round to it sometime today see if there are any shiny spots inside the disconnector hole or sear pin.

mister2
March 24, 2012, 01:23 PM
Opened it up...

Just an immediate eyeball opens up some new possibilities. Shiny spot on upper surface of disconnect (squarish) hole indicates some contact, suggesting the impulse (or vibration) above-referenced. I cannot remember (age does that) ever looking this closely at the Nork's components, but looking at disconnect even with just a magnifying glass makes it look made by hand! The tool marks and uneven surfaces make "angry beavers" work seem CNC-machined. The point being it could very well be off-spec, too

Here's something else: shiny skid mark on the back of the middle sear spring finger corresponds to shiny section of hammer strut, suggesting that as hammer is cocked (post-firing), it contacts spring and sends an impulse to disconnect and on to the trigger.


My first thought is to see whether I can bend the middle finger out of the way and see whether that relieves the slap. Unfortunately, no range testing for at least a week!

1911Tuner
March 24, 2012, 01:48 PM
The middle leaf of the sear spring never leaves the disconnect as it travels up and down depending upon where the slide is, does it?

No. Not unless the trigger moves too far and lifts the spring off the disconnect...and then you've got a whole different set of problems.

The full wedging action of the disconnect then displaces the trigger an equal amount, since the spring does not move.

No. The disconnect sits between the sear and the trigger, and overlaps the sear leg only a tiny amount. Assemble the gun without the grip safety and you can see just how small that overlap is.

Try this:

Empty chamber...slide in battery. Pull the trigger and hold it. Move the slide slowly to the rear. All you'll feel is consistent spring tension against the trigger. There will be no kick back, nor any increase in tension as the disconnect moves down.

I don't know what's causing the trigger to slap your finger, or give you the perception of slapping your finger...but this ain't it.

Rail Driver
March 24, 2012, 03:00 PM
Honestly it sounds to me like poor grip causing the gun to move (more) in the hand during recoil.

Jim K
March 24, 2012, 03:14 PM
To push the disconnector down far enough to do what the OP says, the top would have to stick up 1/4" above the frame and the slide not only would need a hole that deep but could not be installed. I have no idea what is causing that "slap" but it is not as envisioned. FWIW, I have two Norincos and have put thousands of rounds through them without any such experience.

Is it possible that the disconnector is too loose and the cut in the slide not rounded? I can see a possibility that the slide coming back could move the top of the disconnector back instead of down, pivoting the bottom of the disconnector forward to hit the trigger bow and cause a "slap". I grant that is a stretch, and I have never seen or heard of a gun doing that, but it seems possible.

Jim

1911Tuner
March 24, 2012, 03:39 PM
*shrug* I dunno, Jim. This is a new one for me. Wish he lived nearby. I'd like to have a look at it.

mister2
March 24, 2012, 06:33 PM
Tuner et al, your points are considered and accepted. I've abandoned the idea of atomic disconnector :)

Here's what I am now looking at: 1) possibly out of spec hammer strut hitting 2) out of spec middle finger of sear spring. As mentioned above, both have shiny abrasions where potential contact points align. Again, I submit, that at the velocities these parts may be travelling, a slight contact may still amount to a palpable sting. I've bent/relieved these areas and am waiting for next range opportunity to verify.

As for recoil, frame would move backward, not forward, so that's an easy issue to eliminate. BTW, Nork ran through more than 50rds of Tula and WWB and a combination of CMC 8-rd and Pro-Mag (gasp) 10-rd w/o a single malf. Topped mag after loading one in the chamber, too.

In the end, it probably is within window of acceptable performance. Just looking for a piece I can use all day at ACTS or multi-. Maybe I should look at atomic finger, instead.

Any and all welcome to Tucson!

1911Tuner
March 24, 2012, 07:34 PM
The hammer strut is a possibility. One word, though. If a Norinco hammer strut has bent far enough to do what you think it may be doing...it's probably close to breaking. I've had one Norinco hammer strut to break in a relatively low-mileage pistol...so it can happen.

If you decide to replace it, I recommend the OEM Colt strut. It's been redesigned, and although it can no longer be used as a slave pin for the sear and disconnect...it's hell-for-stout, and should outlast the gun.

JRH6856
March 24, 2012, 07:49 PM
You don't by any chance have an old style trigger that does not have the relief cut at the top of the rear bow, do you?

1911Tuner
March 24, 2012, 08:04 PM
All the OEM Norinco triggers that I've seen have the relief cut.

JRH6856
March 24, 2012, 08:06 PM
Just a thought. I had a similar feeling from my 1911 until I replaced the trigger.

mister2
March 24, 2012, 09:01 PM
Someone before me replaced the OEM with a solid aluminum adjustable trigger. And I'm not sure what you mean by relief cut, but the height of the bow is equal on all three sides.

JRH6856
March 24, 2012, 09:30 PM
The back of the trigger bow should have a relief cut about .5 inch long at the top. (http://coolgunsite.com/pistols/parts/wpe4A.gif)

The change was made in 1943 so any newer trigger should have the cut. Not all the aluminum ones I have seen have it.

1911Tuner
March 25, 2012, 09:47 AM
Something else that occurred to me.

Check the disconnect to see if the sear spring has eaten it away into a concave shape on that triangle-shaped lug that it rides on. I've seen that happen, and it makes for some interesting tricks.

That area should be 46 degrees and straight.

mister2
March 25, 2012, 11:24 AM
Tuner, the triangle on the disconnect has not worn into a concave surface. In fact, the piece still bears some rough tool marks. The sear spring has a brownish finish to it and I wonder whether this is OEM or not. The pistol had been pretty much modified by the time I acquired it. NM barrel, alum trigger, beavertail GS (notched to work with a bobbed spur!), wilson-style magwell, 2-pc FLGR and aftermarket heavy barrel bushing. Interestingly, sear and disconnect were left stock. And oh yeah, hardchrome slide notched for (dead, but accurate) Trijicons, and original matte blued frame.

Looks like it was a carry/duty gun at some point judging by the characteristic rub marks on the front of the triggerguard. This must at one time have represented the popular combination of US aftermarket parts with the almost Khyber quality of contemporary Norinco production.

bigfatdave
March 25, 2012, 11:38 AM
Sounds like you inherited Danny Dremel's old gun, or Parts-Swapping Pete, at least.

1911Tuner
March 25, 2012, 12:05 PM
The sear spring sounds like OEM. Also sounds like somebody's tinkered it to death. It's a little like tryin' to unwind a snake from a garden hose.

mister2
April 1, 2012, 12:16 AM
Went to the range today. Trigger slap is all gone. Also noticed that the pistol stayed real steady right after ignition. Previously, there seemed to be some vibration - probably the strut hitting the sear spring as both components went about their business.

The temporary (and maybe permanent, I dunno) solution is to bend the middle finger away (inward) without substantially changing its pressure on the triangular part of the disconnect. It works for now, although, as Tuner commented, the Norinco hammer strut has been known to break and it may be out of spec as I type this. It's working fine, for now.

I'l definitely know what's happening next time I encounter "trigger slap".
Thanks for everyone who chimed in!!

MR2

PS. Now, about those uneven hammer hooks , of which only one is caught by the sear.... I do know this is covered in older thereads so I will NOT raise the issue further. Thanks again!

1911Tuner
April 2, 2012, 06:19 AM
Glad you got it resolved. It's the little things that getcha. ;)

mister2
April 2, 2012, 10:40 AM
Tuner thanks for setting me straight. I was ready to go crazy on the innocent disconnector.

..the little things...

BTW, I discovered the Nork also has a mercury-filled FLGR. Have you ever tried one of these? I could almost swear it made a discernible difference.

MR2

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