rifle firing during trigger reset (periodically)

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[ARCHIVED THREAD] - rifle firing during trigger reset (periodically)

Posted: 7/19/2014 11:16:09 AM EDT

Psa trigger group. Function check is perfect, but will fire occasionally on trigger reset.

Midlength gas 16" barrel with h2 buffer.

Posted: 7/19/2014 12:00:52 PM EDT

[#1]

It is possible the disconnector spring is installed upside down, or the wrong spring. The big end of the spring goes down first into the trigger.

Posted: 7/19/2014 12:14:17 PM EDT

[#2]

Thanks. This is a new problem. The disconnected spring could be the problem though. I have an extra fire control group at home I'll slip in, but would like to get this one sorted, if it is the problem, just because.

Function test is normal though. I can't think of how the gas system might cause the problem, but want to rule out out. Shells are ejecting as I would expect.

Posted: 7/19/2014 12:19:21 PM EDT

[#3]

Check the nose of the disconnector. It could be chipped or worn. (The upsidedown spring is a likely issue too)

Posted: 7/19/2014 12:20:13 PM EDT

[#4]

I think the function test is supposed to be repeated a certain # of times, per the tech manual.

Posted: 7/19/2014 1:22:29 PM EDT

[#5]

I'm not so certain it passes function test.

Squeeze trigger and hold to the rear (catch hammer)
Press hammer back and make sure it holds
release trigger and make sure it doesn't release

That is all good, but if I pull lightly upward on the hammer there is another click.

Disconnector spring is good. Don't have my tools to break down the fcg.

Much obliged for the thoughts. Can anyone eliminate had issues from this and say it is definitely in the fcg? I'm leaning that easy now, but haven't enough experience to be confident. Won't be surprised if the Disconnector is the problem based on the second click and the suggestion to check it's nose.

Posted: 7/19/2014 2:05:22 PM EDT

[#6]

You did not state what receiver you're using. I had a receiver a few years ago that came thru the shop and it acted like it had a tri burst kit installed. After some trigger work it turned out the receiver was miss drilled and the hammer and trigger wholes were just ever so slightly off. You could not tell by eye balling the receiver and the trigger pack went in just like any other AR. That would be the most extreme case problem. Most to the problems I see are the trigger disconnector. Most are a stamped part and some are poorly done at best. Check the hook on the disconnector and the hook on the hammer. they should be sharp but no burrs or ruff edges.

Posted: 7/19/2014 3:04:14 PM EDT

[#7]

Psa receiver as well.

Posted: 7/19/2014 3:07:10 PM EDT

[#8]

Quote History

Quoted:
I'm not so certain it passes function test.

Squeeze trigger and hold to the rear (catch hammer)
Press hammer back and make sure it holds
release trigger and make sure it doesn't release

That is all good, but if I pull lightly upward on the hammer there is another click.

Disconnector spring is good. Don't have my tools to break down the fcg.

Much obliged for the thoughts. Can anyone eliminate had issues from this and say it is definitely in the fcg? I'm leaning that easy now, but haven't enough experience to be confident. Won't be surprised if the Disconnector is the problem based on the second click and the suggestion to check it's nose.

View Quote

How do you know you have the disconnector spring installed properly if you did not take the FCG apart at least enough to remove the disco???

Posted: 7/19/2014 3:13:27 PM EDT

[#9]

You can file the bottom of the front tail of the disconnector to increase engagement.

Posted: 7/19/2014 3:29:28 PM EDT

[#10]

Quote History

Quoted:
You can file the bottom of the front tail of the disconnector to increase engagement.

View Quote

With all due respect, I don't think someone with the OP's experience should start filing on FCG parts. Further more, we don't even know if that is the problem yet. I would like to actually see a picture of the spring he used for the disco. Was the disco spring green?

Posted: 7/19/2014 4:37:19 PM EDT

[#11]

Disconnector spring is green. I know it is in correctly because when I first played with the part kit, that spring caught my interest and I first thought it should go skinny side down. Upon reading the manual I discovered my first intuition was wrong. I also verified by pressing down on the Disconnector and making sure the spring and bottom of Disconnector went completely into the back of the trigger.

I failed to mention I had the hammer spring upside down previously and did end up having the trigger pin walk. Wondering if that damaged the Disconnector. Just thought of that possibility.

I don't think I will be doing any modification to my trigger components. I'd just get new pieces as I don't think I would do considering I struggle to sharpen a knife well.

Also this only started today. Probably have about 500 rounds through it.

Posted: 7/19/2014 5:03:53 PM EDT

[#12]

Okay, just used a small allen wrench as a punch and took down the fcg. The Disconnector spring was definitely in correctly. I'm not sure I like the Disconnector edges but will compare to a brand new fcg once I get home tomorrow. Messing with function testing after reinstalling the fcg, I could not replicate pulling up on the hammer to make a second click. The second click came upon completely relaxing the trigger. I think this is correct.

Eta: spoke too soon. Just replicated getting the second click by pulling up on hammer, not relaxing trigger completely. Also found the fcg would relax completely by tapping/pressing lightly on the trigger pin. Confusing to me.

Really want to take it out to the range to check it tomorrow but unlikely.

I appreciate everyone's help thus far.

Posted: 7/19/2014 11:28:36 PM EDT

[#13]

Why are you pulling up on the hammer when doing a function check? The weapon needs to be assembled (upper and lower together) in order to do the function check as instructed in TM 9-1005-319-10.

FUNCTION CHECK
1. Remove magazine and check chamber. Always check chamber to ensure it is empty and no ammunition is in position to be chambered.

2. Perform function check.

a. Place selector lever on SAFE: Pull and release charging handle. Pull trigger. Hammer should not fall.

NOTE: Slow is defined as 1/4 to 1/2 the normal rate of trigger release.

b. SEMI: Place selector lever on SEMI. Pull trigger. Hammer should fall. Hold trigger to the rear and charge the weapon. Release the trigger with a slow, smooth motion, until the trigger is fully forward (an audible click should be heard; this is the disconnector releasing the hammer as the trigger catches it). Pull trigger. Hammer should fall.

Posted: 7/20/2014 10:03:51 AM EDT

[#14]

I have seen a few problems like this. In all the cases it was caused by the disconnecter and or hammer. If you have an extra I would suggest swapping them out.

Installing. Your hammer spring backwards won't really cause a problem it just changes the spring tension.

Posted: 7/20/2014 10:24:00 AM EDT

[#15]

Happened to me a while ago.Turned out it was the actual pin that holds the trigger in the lower had broken.This seems so hard to believe, because it never fell out, just sat in there broken

Posted: 7/20/2014 12:39:46 PM EDT

[#16]

From what I've seen its gotta be either disco spring installed upside down, disco was machined out of spec, or an issue with your trigger pin. Most cases on this forum I've seen have been the selector spring installed upside down.

Posted: 7/20/2014 6:59:50 PM EDT

[#17]

Quote History

Quoted:
Happened to me a while ago.Turned out it was the actual pin that holds the trigger in the lower had broken.This seems so hard to believe, because it never fell out, just sat in there broken

View Quote

It would be nice if it was the pin, but I pulled out apart and the pin was intact. Should pull it apart and roll it on glass though. Pulled the Disconnector spring and it was installed correctly. I'll replace the Disconnector and am hopeful it corrects the issue.

I'll have to mess with the function test with the upper on.

Posted: 7/20/2014 7:02:37 PM EDT

[#18]

Double

Posted: 7/20/2014 8:19:40 PM EDT

[#19]

Home from the weekend trip. I compared the in place Disconnector to a new one. The nose was rounded on the sides and a hair shorter than the new one. I'm going with the disconnector being worn. Will hopefully be able to verify soon.

Also function checked with upper in place and without; it seemed more crisp (the Disconnector engagement).

Posted: 7/21/2014 12:29:31 AM EDT

[#20]

You might not like it but as a long-time AR/M4/M16 armorer, I'd suggest this:

Scrap the entire FCG. You have a very big problem, both safety-wise and legally. That will attract all the wrong kind of attention if it doubles at the range, whether you mean for it to or not.

For the price, pitch it all and buy a new FCG. I've seen quality go way down after the panic and it's not worth your safety or your freedom to keep messing with it.

[ARCHIVED THREAD] - rifle firing during trigger reset (periodically)

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