Can an AR15 start firing 3 round burst "accidentally"

[Plan2Live]

Can an AR15 "accidentally" begin shooting bursts or does it have to be intentionally modified for this to happen? Let me be perfectly clear from the get go. I'm not looking for details on how to make this happen. In fact, I would prefer yes and no answers without detailed explanation on the inner workings of the AR trigger.

Here's the setup. I was at the range recently and a guy unzipped an AR15 and loaded a magazine. I can't say for certain if he fired any single shots or not but out of the blue he ripped off a threee round burst. Everyone on the range stopped shooting and looked in his direction. He shouldered the rifle and fired again. Another three round burst. At that point the Range Officer approached and asked if he had modified the rifle. He said no but a friend of his had "worked on it" and this was the first time he fired it since then. He was told to button it up and take it off the range and get it checked out.

So, my question is, can an AR "accidentally" start firing burst or does it have to be intentionally modified for this to happen?

 

[R.W.Dale]

Can an AR15 "accidentally" begin shooting bursts or does it have to be intentionally modified for this to happen? Let me be perfectly clear from the get go. I'm not looking for details on how to make this happen. In fact, I would prefer yes and no answers without detailed explanation on the inner workings of the AR trigger.

Here's the setup. I was at the range recently and a guy unzipped an AR15 and loaded a magazine. I can't say for certain if he fired any single shots or not but out of the blue he ripped off a threee round burst. Everyone on the range stopped shooting and looked in his direction. He shouldered the rifle and fired again. Another three round burst. At that point the Range Officer approached and asked if he had modified the rifle. He said no but a friend of his had "worked on it" and this was the first time he fired it since then. He was told to button it up and take it off the range and get it checked out.

So, my question is, can an AR "accidentally" start firing burst or does it have to be intentionally modified for this to happen?

Sounds like a classic example of a jard ar15 trigger in action. AKA "double or nothing" triggers.

The only way I could get mine to not double was to run several times more overtravel and sear engagement than jard recommended. Resulting in a trigger worse than your average parts kit trigger

 

[TurtlePhish]

AR triggers that have been "worked on" by people who don't know what they're doing can have all sorts of problems. Doubles or triples are definitely fair game. It's certainly possible that it was accidental, but two perfect three-round bursts sounds kind of sketchy to me...

 

[plouffedaddy]

If the trigger pins walk out in just the right (or wrong) way---yes it can happen.

 

[TurtlePhish]

If the trigger pins walk out in just the right (or wrong) way---yes it can happen.

If the LPK is installed properly and the pins have notches in spec, they shouldn't move at all. The legs of the various springs in the FCG fit in the notches and hold them in place.

Not saying you're wrong, but it's unlikely. Actually, if the guy removed them and didn't know what he was doing, he might not have put them in all the way or something... but then, it probably wouldn't fire more than one or two shots. Hammer would probably lock up something nasty.

 

[essayons21]

Perfect three round bursts would indicate an M16 trigger parts kit. A malfunctioning trigger that doubles would probably not consistently shoot 3-round bursts. There is always the possibility that he was using a slidefire stock. Did you actually get a good look at the gun?

 

[TurtlePhish]

Perfect three round bursts would indicate an M16 sear. A malfunctioning trigger that doubles would probably not consistently shoot 3-round bursts. There is always the possibility that he was using a slidefire stock. Did you actually get a good look at the gun?

+1 to the inconsistent bursts for a malfunction, but I doubt it's an M16 kit. The GI sear pin hole requires some careful measuring and drilling of the lower receiver. Timing and whatnot. Not to mention the guy probably wouldn't have done that as part of a trigger job, but who knows? Some people do strange things.

 

[taliv]

getting a "3 round burst" is actually kind of tricky. the 3 round burst triggers are much more complex than regular semi-auto or full auto.

getting one to randomly double- or triple-fire can be accidental. it can happen for several reasons. I'd speculate the most common is that many triggers are surface hardened, and when people do bubba trigger jobs that polish through the surface hardening, the metal underneath starts to wear quickly. out of spec trigger holes or pins can also cause the same problem.

if people fired their guns more often, the most common reason would be worn disconnectors. i think i've replaced 2 of them over the past 10 years.

 

[Plan2Live]

I appreciate the input. Way more detail than I was looking for. I did not want to create a How To thread. My reason for asking was to try to deduce if it was reasonable to assume it was innocent and not tampering.

 

[firesky101]

I had a mossburg .22 that would triple when it got dirty. Almost never doubled. Tried to keep it immaculate, but I got tired of worrying about it. Sold it with full disclosure. The guy said he could fix, hopefully that little rifle is still kicking around it was darn accurate.

 

[benzy2]

If it did it every time as 3 rounds I'd say it may be something more, but with the wrong wear/user caused wear doubles and triples can happen. Some adjustable triggers can double if set too light.

 

[plouffedaddy]

If the LPK is installed properly and the pins have notches in spec, they shouldn't move at all

I agree; I was just trying to give a plausible legal reason it could happen.

 

[Ignition Override]

Plan2Live: That guy can count himself very lucky if nobody contacted the friendly Federales about it.

Wasn't a Wisconsin native imprisoned in MN after the judge sided with the ATF's wishes to block clearance for a firearms expert to testify?
Reportedly the firearms expert was aware of slam-fire incidents in perfectly normal, Unaltered ARs. The ATF's motivation always seems to be the implication that a gun must have been altered (not just the green box AR), but not even be able to physically prove so?

The owner's AR had been borrowed and experienced a slam-fire at a WI range.

Although the SKS issue is totally unrelated, these seem to be much more common (free-floating firing pin stuck in cosmoline/dirt), and due to the more pronounced muzzle rise, an SKS owner died at a range in central/northern CA. The article was in "The Sacramento Bee".

 

[Walkalong]

Yes, an AR can double, especially if someone has fooled with the trigger/hammer/sear.

If it happens, do not shoot the rifle again. Take it home, get it fixed by a pro, or replace the trigger group. (Hammer, disconnecter, trigger, and springs)

 

[awgrizzly]

The fire control group of the AR is so well known there's not much reason to not talk about it. Rather, maybe it should be talked about in order for folks to avoid trouble.

The thing can intentionally be made to reliably fire bursts or full auto... reliably is the key word here. It requires full auto fire control parts and an auto-sear. In order to install an auto-sear the receiver needs to have room available to install it and be drilled for the pin. One can legally possess the full auto parts, provided one does not also have a weapon that they can be used in... in other words, if you got both the auto parts and the AR, you can get in trouble. Avoid it! Just drilling the auto-sear pin hole makes the AR a full auto to the BATFE, even if you don't have the auto parts, and can get you broke and in jail. This will show up as an extra hole above the safety lever... you do not want this!

Auto fire can happen unintentionally, but it would be a hit and miss thing... not reliably shooting three shot bursts. But then it's just a random type thing so I suppose a couple three shot groups could happen. There is a part in there called a disconnector that holds the hammer back after it has fired and recocked, as long as you hold the trigger back. This may have broken or been altered by someone adjusting the trigger. When the trigger is released the disconnector lets go of the hammer and the hammer then gets caught by the sear. If the sear doesn't catch, probably because Buba has been adjusting, the gun will fire... mix and repeat. Many have gotten into a pickle at the range because of this.

But without the auto-sear to momentarily hold back the hammer, multi-firing would be erratic. It's a matter of having the hammer pressing on the firing pin at the moment the bolt locks the cartridge into place so that momentum adds enough force to dent the primer. erratic

There's another way to shoot full auto. Instead of pulling the trigger back with your finger, you push the gun and trigger forward as you hold your trigger finger steady. That's not illegal but will likely also get you thrown off the range.

 

[Omaha-BeenGlockin]

If the hammer spring is installed incorrectly---the pin will walk and the malfunction will occur.

So yes--it can happen.

 

[Ignition Override]

awgrizzly: My "gun guru" (former coworker who set some records with ARs) told me that the original "Green Box" ARs attract lots of extra attention, because of what you guys describe.

 

[45bthompson]

Accidentally and reliably? Not likely. Even the m4's our military uses are not totally reliable on burst. And they have a much more complex trigger set up. It is totally possible for some dumbass to screw up a trigger job and create an unreliable runaway gun trigger. You should see all the weird stuff gi's try to get their issued m4's to go rock and roll instead of just burst. I've seen everything from rubber bands and paper clips to hammers with the sear notch ground off.

 

[Float Pilot]

Sounds like somebody installed an A2 trigger system of some sort. (ie three shot burst)

We had a series of unintensional burst when rebuilding a bunch of M-16s into M-16A2s. That happened when the trigger pin or sear pins walked out because some numb-nuts installed the spring legs on the wrong side of the pins. (already mentioned by Omaha-BeenGlockin)
In those cases the rifle would fire two or three and then jam... Or my favorite, it would fire when pulling the trigger and then again when releasing the trigger...
Which made one brand new 2nd Lt go nuts right on the range....

On the other hand, here in Alaska lots of folks have class III firearms and nobody gets their skivvies in a wad about them on the range.

 

[madcratebuilder]

Sounds like his "friend" messed with the disco and the hammer is following until the trigger is released.

NFA AR's are very common in my AO so it would go unnoticed at any range around here. Burst mod is fun for awhile but it becomes a big waste of ammo.

 

[Sky]

Have seen a new rifle out of the box within 100 rounds start 2 and 3 popping. New trigger assembly was installed and problem went away.

 

[brnmuenchow]

Not supposed too.

 

[Kachok]

I cannot speak for the ARs but I had an old worn out 22 that went burst fire and even full auto on me, plungers were worn out so there was nothing stopping the hammer from striking over and over.

 

[txgunsuscg]

Or my favorite, it would fire when pulling the trigger and then again when releasing the trigger...
Which made one brand new 2nd Lt go nuts right on the range....

Yeah, we've had some guns get worn and start doing that. Mine did it, actually, during a course. The instructor was nice enough to look at me and ask me if I did that on purpose. When I told him I had it on Semi and had only pulled the trigger once, we pulled the gun and the armory fixed it later... I would say I've seen 4-5 guns do that, but all of them were high/hard use guns.

 

[paintballdude902]

a buddy of mine tried to do some what of a trigger job on a saiga build... it went burst a few times. we took the trigger parts out and destroyed them and replaced it