Public Service Announcment: check for fire-on-release triggers

[Texas_Mike]

Typically, on a new rifle that malfunctions and fires upon release of the trigger, it is due to an incorrectly installed disconnect spring, and less common, from out-of-spec lower parts. With the trigger at the rest position, and the hammer pushed back until the sears are at their closest position, there should be a gap between 0.001" to 0.003", no more. If the distance is greater, and the lower parts are within verified tolerances, than an out-of-spec receiver with poor pin hole placement is considered as the culprit. If this is the case, then replacing lower parts may temporarily alleviate the symptoms of this issue, but the malfunction will ultimately return. Measuring these components and verifying critical dimensions, as well as verifying that they are within specification by evaluating their functional relationship with one another, is important when attempting to troubleshoot an issue like this.

[Ned Christiansen]

M-16. If you have the auto sear, which can be detected from the exterior by the presence of the auto sear pin over the selector, or if the receiver has the pin hole and will accept an auto sear, even if it’s a stripped receiver with no parts in it whatsoever, it’s a machinegun. A selector that rotates 180 from "safe" as shown in the pic could be a hint that something's different. In a standard semi-auto set-up the selector is prevented from going to that position.


Auto parts on right, semi-auto parts on left. Note the “busy” selector—it has a few more features because it has a few more functions. Notice the hook at the top of the hammer, the long-tailed disconnector, and the open-backed trigger to make room for the disconnector’s long tail. My opinion, my advice, would be, “don’t have any of these in your semi-auto AR-15". Again I’m no expert on the regs and this is not genuine legal advice. Just saying, if it’s not papered as a machinegun, it would seem a good idea not to have any machinegun parts in it, although an M-16-style carrier alone, is specifically allowed.


Semi-auto trigger and disconnector left; auto parts right. Again note on the auto parts, the disconnector’s long tail and how the open back of the trigger allows it to fit in place. On the semi-only parts, the disconnector tail is shortened so a select-fire selector cannot act on it, and the wall at the trigger body’s rear prevents the installation of a long-tailed, select-fire disconnector.

[Ned Christiansen]

This is pretty good too, I don't know the source:

[Eurodriver]

Just seeing this thread now.

I actually had this issue with a complete lower from a very well known manufacturer on this forum.

It surprised me because it didn't do it every time, and the first time it happened I thought "I didn't just pull the trigger twice??" This was very difficult to diagnose because it wouldn't happen consistently and would often happen during rapid strings of fire. One day I was doing slow fire and noticed it fired as I released the trigger and knew I had a problem.

Luckily this was taken care of by the manufacturer but I can certainly attest that it does happen even to the very best manufacturers.

Great thread.

[williejc]

Although I have been shooting ARs since 1981 and have owned several(including my one current Colt rifle), I'm not an AR guy, which means that I am mechanically ignorant of the platform if anything other than field stripping is necessary. My question is this: are police armorers trained to check for the problem? What about military armorers? IG, please chime in and share your experience. Have you seen many examples of this malfunction among military M16s?

[Ned Christiansen]

I'd be curious too as to IG's answer but will hazard a guess it will be "no". I feel it a safe bet to say that a few manufacturers, those making guns for the G among them, understand and check for the issue.

[usmcvet]

Clint thanks for pointing me to this awesome sticky. I need to review the stickies.

Thanks Ned.

Just seeing this thread now.

I actually had this issue with a complete lower from a very well known manufacturer on this forum.

It surprised me because it didn't do it every time, and the first time it happened I thought "I didn't just pull the trigger twice??" This was very difficult to diagnose because it wouldn't happen consistently and would often happen during rapid strings of fire. One day I was doing slow fire and noticed it fired as I released the trigger and knew I had a problem.

Luckily this was taken care of by the manufacturer but I can certainly attest that it does happen even to the very best manufacturers.

Great thread.

I had this happen to me esterday when I was trying to hit a clay pigeon at the 50 yard line with my 9mm AR. I was slowly releasing my trigger. The gun also went full auto a few times. I can now get it to do it 100%!of the time with a functions check. The slow release is key.

https://www.m4carbine.net/showthread...ew-times-today

I'd be curious too as to IG's answer but will hazard a guess it will be "no". I feel it a safe bet to say that a few manufacturers, those making guns for the G among them, understand and check for the issue.

I've been to several AR armorers courses as a cop. I don't think this was discussed.

Try imgur. I use it for all the Arisaka images that get posted on forums. Very easy drag and drop interface and none of that weird indirect linking crap that photobucket has.

That's a great tip too. Photo bucket used to be great but it's a PITA now. Especially from a phone or tablet.

[JerDerv]

I had to do this on a PSA EPT trigger. Wish i had seen this thread and checked before going to the range. Had a few doubles and had to go home early.

[tb-av]

Anyone having difficulty seeing how things work this is a good video. Thanks for the instructions. Mine all "clunk" as intended but glad to know a fix if I ever need it.

https://www.youtube.com/watch?v=xh2FjzVVIZY

[Ppowers1010]

Thanks for the info, haven’t had this problem before but I’m about to check my newest builds now!