AR 15 Malfunction.

sic65stang

Sergeant
Full Member
Minuteman
Dec 29, 2010
251
1
38
Virginia Beach, VA
I was out shooting today and on the last round of the magazine the round failed to fully chamber, however would not extract. Once the bolt was broken free from the casehead, I released the bolt to try to chamber the round. Instead of fully chambering, the round fired. Fortunately all safety precautions were taken so noting bad happened, but what do you guys think may have caused the malfunction? Why would the rifle slam fire, it has never done that before? It was hot here today and this was after extensive shooting, could it just have been too hot? Is there any way to make ar15’s more reliable when hot? Thanks
 
Re: AR 15 Malfunction.

Did you by chance get a look at the previous round(s) that went through the chamber?

Were these reloads? Is there any chance there is a neck stuck in the chamber?
Do you know how far it fed into the chamber before it fired?

How hot was it? Any chance it was a cook-off?
Did you shoot anymore after the incident?

I'll be curious how this works out for you.
 
Re: AR 15 Malfunction.

The rounds were reloads and I didnt get to look at the other rounds. I looked at the one that was stuck after I got it out, looked a little pressured but not too bad considering it was not fully chambered.

I do not think it cooked off. I think it stuck because of the base. I do not yet use the small base dies for my AR, I have never had an issue.

I noticed it was jammed because it did not fire. The bolt was stuck in the forward position. I pressed back forcefully on the charging handle to release the bolt. I locked the bolt to the rear, checked the round (the primer was not punched) and pressed the bolt release. the bolt rode forward and the round fired. Again I forced the bolt rearward and noted the firing pin divot on the primer.

I will be out again tomorrow. The rifle seems to function empty flawlessly now, and there is no binding in the BCG so I have no idea what could have been the issue.

I presume the reload was slightly too large at the base in to fully chamber, but why would it not release, and why would it fire when the bolt was released forward?
 
Re: AR 15 Malfunction.

Hat's off to you for the safe handling. I wonder if the hammer released? I guess there is no way to tell, but that would seem more likely than than the free-floating firing pin generating enough force just from slamming home.

Hopefully this gremlin is dead.

Good luck.
 
Re: AR 15 Malfunction.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: snajpr</div><div class="ubbcode-body">Hat's off to you for the safe handling. I wonder if the hammer released? I guess there is no way to tell, but that would seem more likely than than the free-floating firing pin generating enough force just from slamming home.

Hopefully this gremlin is dead.

Good luck. </div></div>

+1

I was out shooting with my dad one day at our lease. The roll pin for the trigger on my AK slipped out; and when I charged the weapon, it slam fired 3 rounds into the dirt 10 meters in front of me.

It was a HUGE reinforcement to me about why I always follow the rules. We follow the rules all the time, but it's stuff like that which will show you about how catastrophic it could have been if you didn't.

Also, the AK is fixed now, the sheppard's crook had snapped. It was promptly replaced with a an all steel one rather than the wire thing.
 
Re: AR 15 Malfunction.

Due to the chambering issues and knowing that these were reloads, my money is on the ammo being the problem, specifically, a high/soft primer. What type of primers did you use?

As to your chambering problem, it could be that you need small base dies. However, most rifles function just fine without using small base sizing dies. Most likely, that case was not sized properly. Do you use a case gauge or comparator to setup your dies? If not, you just may not be bumping the shoulder back far enough to ensure reliability.
 
Re: AR 15 Malfunction.

Free flying bolt struck a stalled round. Neither condition was normal. The situation looks like a classic instance of a slam fire.

In the future; remove mag, lock back bolt, and try to extract the stalled round by prying against the extraction groove..

If this is not possible, gently guide the bolt forward to meet the cartridge base using the t-handle, then open the upper and remove the BCG. Gently ease the cartridge out of the chamber using a cleaning rod. If it will not respond, try to pry it out by the extraction groove.

The problem occurred because the bolt was allowed to fly free at a stalled round. This defeats the design safety features which expect the bolt's velocity to be curtailed by the friction/drag caused by feeding a round from the magazine. IMHO, most slamfires are caused by improper handling. A bolt should never be allowed to fly free toward a chambered or partly chambered round.

This is not likely a heat issue.

Raised primers are more likely to cause a misfire than a slamfire.

Until a primer is fully seated the anvil legs have not properly preloaded the priming pellet, sensitizing the primer. Most usually, the first firing pin strike completes the primer seating process, but also absorbs enough energy from the firing pin that it is unable to fully initiate ignition. Generally, the primer will ignite on a subsequent second strike. This 'second strike ignition' syndrome generally confirms the presence of an incompletely seated primer.

Greg
 
Re: AR 15 Malfunction.

This is an ammo problem, not a rifle problem.

This is not a cook off. Which occurs when a chamber is so hot the round fires. This round wasn't chambered.

Next time you have a failure like that eject the round and move on. Don't sit
there trying to rechamber a round that already showed signs of malfunctioning.
 
Re: AR 15 Malfunction.

It was CCI primers. I am almost positive I got a batch of second hand ammo that required better base sizing. I need to order a set of small base dies to use with secondhand brass. I have never had an issue with this with any other rounds I loaded. Today at the range I had a similar stoppage. The round did not fire this time, but rather when the bolt was forced rearward the loaded round ejected. Does anyone know of a better way than forcing the charging handle rearward to release the bolt from a stuck casehead?
 
Re: AR 15 Malfunction.

What type of CCI primers, #41 or #400? The #400 have a relatively thin cup on them and coupled with not being seated deep enough is the likely explanation for your slam fire.

I would not use any more of them before identifying and fixing the cause of your malfunctions rather than focusing on how to clear those malfunctions.

However, to answer your question, no, there is not another recommended way of extracting a round other than using the charging handle.

Is this a different rifle than you have loaded for in the past? If you have loaded for this rifle before using a standard FL sizing die, I am curious what about this brass makes you think you need small base dies now. You also didn't say whether the ammo had they been checked in a case gauge.
 
Re: AR 15 Malfunction.

I have had stuck rounds before from experimenting- unsuccessfully obviously- with neck sizing for an AR. Yeah, I know it wasn't the brightest idea. The solution was to pull the rounds apart, FL size them, and reload.

I have used CCI Primers for years (most available) and never had an issue. I could see one though if the pin caught a soft one. After all, we have all seen the slight mark on an unfired round where the firing pin bumps it during the firing process.

I also think it not being fully chambered may have contributed. The camming action of locking the lugs on an AR slows the BCG down in the last portion of the chambering and probably reduces the momentum of the pin. If it is stopped suddenly before then the pin would have more energy and the buffer spring is still driving the BCG as well.

This is just my idea of what happened.