AR-15 style SAFETY ALERT

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Posted here on OCDO because all four of us present are members of this board and ANY firearms safety issue such as this is important to ALL firearms users.

This is an excellent lesson in just why muzzle discipline/awareness as well as trigger finger discipline is so important with firearms.

Smith and Wesson M&P 15 (their AR-15 model). Round fired while safety lever was in the "SAFE" position.

This just happend to my wife today. Four of us were on the range and I was supervising my wife firing her new AR. She had it on "SAFE", magazine inserted, charged the chamber, aimed and attempted to fire. Observing, I did not inform her the safety was still "SAFE" so that I could observe her technique at trigger pull and see if she was jerking the trigger or anticipating the recoil.

Imagine my surprise when she squeezed the trigger and the round fired!!!!!!!!!!

I immediately took control of the weapon while it and she remained in place and made a safe weapon (removedmagazine,cleared the chamber, bolt locked to the rear). I then operated the safety lever to "FIRE" and back to "SAFE", hand loaded a single round and attempted to fire. The trigger moved, the hammer fell, but no discharge. Cleared the chamber and observed an obvious dent in the primer.

I reloaded the same round and repeated with no firing resulting but again, the trigger moved fully and the hammer fell.

I recharged the weapon with the same round andstruck the forward assist 3 times, aimed and the rifle fired.

I installed a new round and struck the forward assist three times, aimed and the weapon fired while in the "SAFE" position on the first attempt.

I repeated with a third round with the same results, fired on first attempt.

I made a safe weapon and then separated the upper and lower receivers. The hammer was observed to be at an odd angle and repeatedly fell when the trigger was pulled in the "SAFE" position.

Closer examination revealed that the through receiver pin on which the hammer rotates had slipped (from left to right) so that it was only supported on the right side of the receiver. This allowed the hammer to twist inside the receiver and apparently renders the safety inoperative.

After reinstalling the pin correctly, the weapon was tested while disassembled and functioned properly as regards the fire/safe lever and hammer release. Reassembled the weapon and had no further problems.

This weapon is only two weeks old and has just under200 rounds of factory ammo through it but 120 of those rounds were "bump fired" over the course of a week on two separate occasions. After the range time was over it was realized that the last three full magazines (90 rounds) through the weapon had all been "bump fired".

My conclusion is that the "bump firing" caused the pin to move in the receiver allowing the hammer assembly (including the disconnector and sear) so that the safety lever was not capable of properly engaging. With the hammer twisted slightly in the receiver it was not able to deliver a consistently sufficient impact to the firing pin to actuate the primer without the forward assist being struck. It is not clear if my wife had stuck the forward assist when she charged the chamber but that is how I've taught herin familarizing her with the weapon so it is most likely that she did. This would account for the difference in (faulty) operation when I initially tried to fire without use of the forward assist.

I will be inspecting the orientation of the pin after bump firing as well as before, during, and after, regular firing to see if the problem persists. I will also be contacting the manufacturer and will consider "staking" the pin depending upon their reply.

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The safety on an AR-15 is a trigger block. The trigger should not be able to pull when selector is in safe position. The hammer should have nothing to do with it. If the trigger moves while on safe:

1) the rear portion of the trigger that is intended to interfere with the selector is missing (ground away, broken off, etc)

2) the selector has a section ground out of it where it should not have been. Did someone try to make an M-16 selector out of it and not know how? A proper AR-15 selector is cylindrical and has only one flat spot, which is presented to the rear of the trigger only when in the fire position.

3) some very drastic way out of spec mis-location of the selector hole that allows trigger travel. i.e., the selector is located too far up on the receiver, by a quite significant amount that I doubt any QC person would have allowed. Does the detent snap? Or does the selector move freely? That would be a clue.

I can't think of anything else. This problem should be very conspicuous simply by popping out the rear take-down pin and having a look inside.

It is possible that a similar condition existed with the trigger, and you incidentally rectified it while dealing with the hammer. I'd double check the trigger pin to ensure that it is not borderline.

There are various brands and types of anti-walk pins available in the aftermarket. You wouldn't be the first to discover that bump-firing sometimes requires them.

I recommend these: http://www.midwayusa.com/viewProduct/?productNumber=539753

The ones that have the tiny screws can come unthreaded or break the itty bitty screws, not recommended.

No doubt, contact with the manufacturer will result in the same suggestion.

You cannot, and should not attempt to, stake a steel pin against aluminum. The thin layer of anodization will flake off, and the pin may appear retained for a while, but you will have cracked the anodization from the surface, even inside the hole. It will result in elongation and over-sizing of the axis hole. It'll seem fixed at first, but time will show you that the receiver has been ruined, possibly beyond (reasonably priced) repair. I'll say it again; DON'T DO IT.

Just buy the anti-walk axis pins. They're cheap.

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As I said in the OP, it's a NEW weapon. Less than 2 weeks off the shelf andless than 200 factory rounds through it. No one has attempted to alter it into a full auto. Bump firing entails rapidly actuating the trigger manually by any of several means to give a high rate of fire from a semi-auto. It has been bump fired but no modifications have been made.

I have visually inspected, without disassembly, the selector, trigger, and sear. All appear as new with no wear or breakage.

I did 18 years in the Marines so I'm quite familiar with the internal workings of the M16 from which the AR is derived. 2 1/2 years of that I was an armorer. I'm certain the problem wasthe pin in the lower receiver that the trigger pivots on falling into the receiver on the left side allowing the hammer to deflect towards the left which then allowed the slight amount of trigger movement that is present in SAFE to allow release of the hammer.

If the weapon were an older one with many rounds through it I'd simply stake the pin to prevent it moving and attribute the malfunction to wear. Since it's brand new, this shouldn't have ocurred and is a potential safety hazard in all similar models hence the message here. I've already written to the manufacturer so we'll see what they say, hopefully tomorrow.

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I did not intend my post to be condescending. There were simply some key elements that stood out.

1) The trigger moves on safe. That just plain shouldn't happen. You have more than a hammer pin problem.

2) You made no mention of addressing this

3) Stake Anodized aluminum against a hardened steel pin? Surely, you jest?

I don't think I'd build an AR-15 with standard pins. I always use the pins I linked in the previous message. No possible way to have a problem like this with them.

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I didn't take it as condescending and didn't mean to imply that I had. My appologies as it apparently sounded like I took your coments poorly, I did not. No harm, no foul?

The trigger moves SLIGHTLY which is normal in my experience with M16 and AR15 weapons but I'm going to go to the store where i bought it and check one off the shelf.

I would stake the pin itself, center punch it to slightly spread the end and tighten the interference. I will NOT do that without checking with the manufacturer (letter is sent) and/or a gunsmith.

I don't like any of the pins in this weapon after this incident. The take down pins are so tight you have to use a punch/round/ink pen to get them far enough out to pull them with your fingers. On that, maybe I'm just used to worn out "unit armory" weapons. There is no way I could break this one down and reassemble in 90 seconds let alone blindfolded as I've done on numerous occasions in the past.

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We-the-People wrote:

I didn't take it as condescending and didn't mean to imply that I had. My appologies as it apparently sounded like I took your coments poorly, I did not. No harm, no foul?

The trigger moves SLIGHTLY which is normal in my experience with M16 and AR15 weapons but I'm going to go to the store where i bought it and check one off the shelf.

I would stake the pin itself, center punch it to slightly spread the end and tighten the interference. I will NOT do that without checking with the manufacturer (letter is sent) and/or a gunsmith.

I don't like any of the pins in this weapon after this incident. The take down pins are so tight you have to use a punch/round/ink pen to get them far enough out to pull them with your fingers. On that, maybe I'm just used to worn out "unit armory" weapons. There is no way I could break this one down and reassemble in 90 seconds let alone blindfolded as I've done on numerous occasions in the past.

Click to expand...

I am a gunsmith... Not like that is anything special. I also don't own any AR-15s, I just build 'em and fix 'em. ;-)

I consider the anti-walk pins to be Standard Issue. It's $5. Really. Why fool around making a booby trap on a pin you might want to remove, or a future owner?

I'd say that a little graphite/lithium grease is in order for all detented pins, especially the take-down pins. Applied to the pointy end of the detent before shoving it in the hole. Just about all of them are 'can't do it by hand' tough when they are new.

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ixtow wrote:

We-the-People wrote:

I didn't take it as condescending and didn't mean to imply that I had. My appologies as it apparently sounded like I took your coments poorly, I did not. No harm, no foul?

The trigger moves SLIGHTLY which is normal in my experience with M16 and AR15 weapons but I'm going to go to the store where i bought it and check one off the shelf.

I would stake the pin itself, center punch it to slightly spread the end and tighten the interference. I will NOT do that without checking with the manufacturer (letter is sent) and/or a gunsmith.

I don't like any of the pins in this weapon after this incident. The take down pins are so tight you have to use a punch/round/ink pen to get them far enough out to pull them with your fingers. On that, maybe I'm just used to worn out "unit armory" weapons. There is no way I could break this one down and reassemble in 90 seconds let alone blindfolded as I've done on numerous occasions in the past.

Click to expand...

I am a gunsmith... Not like that is anything special. I also don't own any AR-15s, I just build 'em and fix 'em. ;-)

I consider the anti-walk pins to be Standard Issue. It's $5. Really. Why fool around making a booby trap on a pin you might want to remove, or a future owner?

I'd say that a little graphite/lithium grease is in order for all detented pins, especially the take-down pins. Applied to the pointy end of the detent before shoving it in the hole. Just about all of them are 'can't do it by hand' tough when they are new.

Click to expand...

I agree ixtow...Use the anti-walk pins and don't stake them!