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Old December 29, 2018, 01:06 PM   #1
Kvon2
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Double Fire..

Hi all,

I took my BCA 7.62x39 AR out to the range today and experienced a few double fires. At first I figured I left my finger in an odd position so maybe I had accidentally bump fired it. It happened two more times and I packed up the rifle for the day before gaining the attention of the range master.

I did recently install a PSA enhanced polished milspec trigger(I don't remember the exact name but It was around $40). It came with two springs and I used the lighter one. This was my first time firing the rifle with the new trigger.

What gives here? I never had this issue with the old trigger. Should I swap out the spring and hope that does the trick? Or should I just throw the old trigger back in?
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Old December 29, 2018, 01:15 PM   #2
ed308
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The trigger seems like the obvious problem. Make sure you installed it correctly. If so, then go with the heavier spring. But I'd call PSA to see if they've had a problem with the trigger doubling. The first AR I assembled would double. My problem was the gas key on the bolt was out of round.

Last edited by ed308; December 29, 2018 at 03:51 PM.
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Old December 29, 2018, 03:34 PM   #3
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I went through a similar occurrence with my buddies newly built AR-15 with a very light target precision trigger group. His first range trip yielded 2 separate unintentional double taps. I was shooting next to my buddy. We inspected the trigger group and things looked correct. I shot about 30 rounds at various speeds and I had no issues with double taps. Long story short it was my buddies shooting hold and methods causing bump fire type double taps. We were shooting benchrest and my buddy was not shouldering the rifle tight enough, and also jerking the trigger causing his finger to abruptly bump fire. After tightening up his hold, and proper trigger pull and follow through the rifle functioned as it should. Try and have another shooter fire your rifle. This might isolate the issue to either mechanical malfunction or shooter induced issue.
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Old December 29, 2018, 03:54 PM   #4
Kvon2
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While I accept that it could be a me problem, I don't think it's likely.

I've never had this issue with any other rifle or even this same rifle until the trigger change.
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Old December 29, 2018, 06:48 PM   #5
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Quote:
Originally Posted by Kvon2
While I accept that it could be a me problem, I don't think it's likely.

I've never had this issue with any other rifle or even this same rifle until the trigger change.
I believe it's possible to install the AR-15's trigger spring upside down causing double taps. Might want to perform a quick inspection.
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Old December 30, 2018, 07:31 AM   #6
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TRIGGER MANAGEMENT

"While I accept that it could be a me problem, I don't think it's likely."
Well, yes it is likely that either your installation or trigger management is faulty.
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Old December 31, 2018, 06:31 PM   #7
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I experienced a double fire with a friend's Ruger AR rifle. The culprit was the trigger pin walking.
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Old December 31, 2018, 07:52 PM   #8
stagpanther
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Quote:
The culprit was the trigger pin walking.
Good suggestion--the EPT is such a basic trigger (I've installed 3 of them) it's hard to imagine a scenario where it could be doubling with proper installation--but if the hammer to trigger alignment goes out of whack I could see the hammer not being let off properly on reset. Obviously you want to do the complete fire control group check. I assume you are using a dedicated 7.62 x 39 BCG, I thought about the possibility of a heavy firing pin strike upon chambering--but my experience has been the opposite with AR 47's--I've had a few FTF strikes but that was with thinner/lower federal primers.

BTW--you say it came with two springs--should have 3 including the hammer, disconnector and trigger springs
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Last edited by stagpanther; December 31, 2018 at 08:04 PM.
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Old December 31, 2018, 08:48 PM   #9
Kvon2
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So sure enough I took a look at the rifle just now without even opening it up and could see the trigger pin has been backed out.

What's the fix?

I mean to stop it from backing out in the future...new pin?
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Old December 31, 2018, 08:56 PM   #10
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non-rotation pins can't "back out"
Having a FCG pin "back out" is one of the things that I've not experienced. I'd suggest you may have failed to get the pin(s) seated with the springs in the retainer grooves.
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Old December 31, 2018, 09:23 PM   #11
Bartholomew Roberts
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The leg of the hammer spring should prevent the trigger pin from walking. I’d check to see if you installed everything correctly.

Additionally, any time you mess with the fire control group in an AR15, you should conduct a functions check before live fire.
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Old December 31, 2018, 10:21 PM   #12
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I've heard of anti walk-out trigger pins, but I don't know anything about them. May be worth a look.

Interestingly, my friends Ruger AR556 is the 1st and only AR I've ever fired and in the 1st mag that I shot, I experienced the double tap. He knew right away what the problem was as he warned me ahead of time that he had been noticing the pin "walking" during previous outings with the rifle. It was very subtle, but you could feel the pin protruding from the right side of the receiver with the trigger finger.
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Old December 31, 2018, 11:03 PM   #13
Bartholomew Roberts
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Every time I’ve seen an AR double, it has been one of two things.

1) Poor trigger control causing unintentional bump fire.
2) Through DIY gunsmithing, use, or poor parts quality, the thin case hardening on the nose of the trigger has been worn through and now it isn’t catching the hammer after the disconnector hook lets go, so it fires on the pull and the release. Basically a DIY binary trigger; but less predictable.
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Old January 1, 2019, 12:04 AM   #14
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Quote:
So sure enough I took a look at the rifle just now without even opening it up and could see the trigger pin has been backed out.

What's the fix?

I mean to stop it from backing out in the future...new pin?
I wouldn't go as far as to say "it can't happen" but it's rare if the hammer spring legs sit in the grooves on the trigger pin. I've seen it happen though--for example some Jard adjustable triggers require the installation of a "spacer lock plate" to restrict side-to-side movement of the pin. A basic trigger like the EPT really shouldn't need anything special, but there are after-market anti-rotation/anti-walk pins you can get. After assembly and doing your function check, you can also lightly push the pins from the side to see if they readily slide in the receiver--other than maybe a slight thousandths of an inch or so it should resist sideways movement.
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Last edited by stagpanther; January 1, 2019 at 08:07 AM.
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Old January 1, 2019, 08:00 AM   #15
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"Additionally, any time you mess with the fire control group in an AR15, you should conduct a functions check before live fire."

Very important info right there. Far too often the "function check" involves a fully loaded mag and unwarranted expectations. IMHO, it's amazing that more "run aways" don't occur.
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Old January 1, 2019, 08:39 AM   #16
stagpanther
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Quote:
Every time I’ve seen an AR double, it has been one of two things.

1) Poor trigger control causing unintentional bump fire.
2) Through DIY gunsmithing, use, or poor parts quality, the thin case hardening on the nose of the trigger has been worn through and now it isn’t catching the hammer after the disconnector hook lets go, so it fires on the pull and the release. Basically a DIY binary trigger; but less predictable.
Really--it's not all that hard to see how the hammer might not let off on the trigger properly when you consider that the trigger is essentially a "see saw" mechanism on the the trigger pin. A change of just a few thousandths of an inch +/- in that degree of rocking--and where it stops--can easily alter sear and disconnector timing. Lots of different parts go into the overall assembly--just because something is "Mil-Spec" doesn't mean it's guaranteed to fit and function properly with everything else that is.

Good luck Kvon and let us know how it goes. x39 in an AR can be an interesting experience; my experience hand-loading lots of ammo for both it and the AK is that generally most people are happy if it groups around 2"--but if you're willing to put the time and money into it you can tune that down to MOA or a bit less; but for the most part options are very limited on the performance of the cartridge. I've pushed bullets much faster than the commonly found 2300 to 2400 fps--but have yet to adequately stabilize the stubby little flat-base bullets in the process of doing so and maintain good accuracy/consistency. I don't know if you reload--but if you do make sure you segregate AR47 spec cases from the AK ones--AK's tend to be more "destructive" with the brass--changes in the head area of the AK case may preclude it from being reliably usable in an AR47 reload.
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Last edited by stagpanther; January 1, 2019 at 08:48 AM.
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Old January 1, 2019, 01:25 PM   #17
Kvon2
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Just took it apart and see no installation issues.

My guess is I did not get the trigger pin all the way in the first time as I am unable to replicate the issue while function checking.

I'll get it back out to the range in coming weeks and see what happens.
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Old January 2, 2019, 11:27 AM   #18
El_Cabra
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Maybe the polishing was a little over done?
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Old January 2, 2019, 01:54 PM   #19
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The enhanced polished "milspec" trigger and light springs are probably the cause. The "until the trigger change" statement pretty much confirms it. I'd put the other spring in and if that doesn't fix it call PSA.
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Old January 2, 2019, 07:08 PM   #20
Kvon2
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I think it is that the trigger pin either backed itself out or was not pushed in all the way upon install and I missed it.

Hopefully the problem is now solved.
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Old January 2, 2019, 08:59 PM   #21
stagpanther
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I'm pretty familiar with the EPT trigger group--there's a misconception that it's a "reduced power" spring set-up--it isn't, just as they say in the product description it's a Nickel plated hammer and trigger with the sear and trigger contact surfaces finely polished. Other that--it's pretty much just another ho-hum standard fire control group--but smoother. I'd say the polishing takes maybe a lb +/- of pull off your standard mil spec plain Jane group. For an inexpensive woods hunter build where you might also being wearing gloves--it's an excellent group IMO. You can further improve the pull ,take up, over travel etc if you wish but that means buying and adding other replacement components.
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Old January 3, 2019, 12:39 AM   #22
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Trigger Pins
These are similar to mine but cost less. The trigger pins will not loosen with pink locktite on the screws.
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Old January 3, 2019, 08:10 AM   #23
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"For an inexpensive woods hunter build where you might also being wearing gloves--it's an excellent group IMO."

I concur, it's my opinion that a "too light" trigger pull contributes to the "doubling" that seems more prevalent these days. My muffled coyote shooter has a 3.5-4# pull and requires care to prevent letting a shot go prematurely when wearing gloves.
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Old January 3, 2019, 11:40 AM   #24
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It's very rare, but a "double" can happen with my standard, original AK triggers (Maadi, AMD-65, MAK 90, SAR-1) , even with my Yugo M59 SKS...

...when a gun is shouldered against a soft, winter jacket using standard 'pressure'.
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Old January 3, 2019, 05:36 PM   #25
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I've had these doubles and even triples happen to me twice with two different rifles . First time it happened was with a Del-Ton 316 complete NIB rifle on the first range trip . I'd get doubles on very slow trigger release and it was repeatable with both me and a friend shooting it . Since it was a new complete rifle I sent the whole thing back and it was returned with new hammer and disconnect with the explanation they were out of spec . It's been one of my most reliable firearms since .

The second time it happened it was on my NM build again first time out . This rifle however has a Geissele high speed national match trigger with a 1# second stage . The issue was my trigger control and has never happened again since I learned how to pull that trigger correctly .

There are many reasons this can happen to include improper installation . Not sure I'm buying the pin walking though . Everything should stay lined up until the pin fully clears one side of the receiver , yes/no ? I've had pins walk before , never noticed a difference in firing ( always caught it before it cleared one side )

I did function test on both before heading to the range and both seemed fine . That was how ever very basic function tests . I now do a much more detailed test on new builds .
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