Ar-15 primer blow-out


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Rich_Lather
October 19, 2008, 09:15 PM
I went to the range today to sight in my new ar15. I was within inches of bullseye at 100 yards when the gun jammed, breech closed. I could not pull the charging handle back more than a wee bit--with both hands, butt on chest.:cuss:

I took it home to look at it and hammered a cleaning rod in the barrel to open it. It looks like it blew out the primer and jammed everything. Have you heard of such?

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rbernie
October 19, 2008, 09:32 PM
What ammo were you using?

Oh, and next time - smack the rifle buttfirst into the ground (dirt, preferably) while pulling back on the charging handle instead of trying to hammer the case out from the muzzle. Hitting the rifle butt-first into the ground is called 'pogoing', and it uses inertia to help pop the stuck case loose.

It works.

stubbicatt
October 19, 2008, 09:36 PM
I've heard of such things, yes. Whether it is the rifle or it is the ammo, I don't know. If you are shooting commercial reloads, sometimes they use softer primers which are ignited by the firing pin on closing of the bolt. I don't know if this is your situation, or whether you simply had an overcharged cartridge.

Rich_Lather
October 19, 2008, 10:08 PM
I was using a commercial reload from Georgia arms. It wasn't a slam-fire, though...I was sighting in nice and methodical-like.

Thanks for the pogoing suggestion. Hopefully, this won't happen again, but if it does, it won't be game over.

I personally didn't like the thought of the rod and hammer method, but....

briansmithwins
October 19, 2008, 10:57 PM
Slam fire doesn't refer to the rate of fire, it's caused by the action of the bolt closing on the cartridge: either a high primer or a stuck firing pin can cause a slam fire.

I personally don't shoot reloads. If I don't know what lot it came from, I don't shoot it either. BSW

PvtPyle
October 19, 2008, 11:30 PM
Hopefully you were not shooting 5.56 in a .223. The freebore length in the .223 is much shorter than that of the 5.56, and NATO ammo is several hundred fps faster (which means higher pressure) than the SAMMI stuff.

It is not uncommon to see this issue when you shoot 5.56 in .223. So check your ammo first.

If that is not the issue, get a set of GO and NO-GO gauges and check your head spacing. It is not common, but every once in a while you will get one from the factory cut wrong. That could also be an issue.

Keep us posted on what you find.

taliv
October 19, 2008, 11:41 PM
none of this is making sense to me.

seems odd that a round hot enough to pop a primer would get stuck and be unable to be moved. normally, these rounds cycle the action even more forcefully.

I have never had to morter or pogo a fired case. it's always unfired, live rounds that get stuck as described.

my question would be... did the primer come from the round you hammered out or the previous one?

and my suspicion would be that georgia arms needed to trim that case before reloading it

PvtPyle
October 20, 2008, 12:03 AM
When the 5.56 round gets jammed into the chamber of the .223 barrel, the case neck gets forced into the lands and grooves because of the short freebore distance. When the round is fired, it is jammed to the point that you have to beat it out with a rod and hammer.

YMMV, but check that and let us know.

P-32
October 20, 2008, 01:04 AM
Sounds to me like a reloaded case you were using had a loose prmer pocket. Federal 223 brass is well known to have this problem. While I have not had the rifle jam up, I have had a primer work it's way into the trigger group and foul things up.

nicholst55
October 20, 2008, 04:34 AM
Sounds to me like a reloaded case you were using had a loose prmer pocket. Federal 223 brass is well known to have this problem. While I have not had the rifle jam up, I have had a primer work it's way into the trigger group and foul things up.

+1. This is common enough.

taliv
October 20, 2008, 09:12 AM
When the 5.56 round gets jammed into the chamber of the .223 barrel, the case neck gets forced into the lands and grooves because of the short freebore distance. When the round is fired, it is jammed to the point that you have to beat it out with a rod and hammer.

sure, but how is that related to a blown primer?

PvtPyle
October 20, 2008, 09:43 AM
Over pressure. The gases take the path of least resistance. See last months SWAT mag for an in depth examination of this very issue.

SlamFire1
October 20, 2008, 09:57 AM
Without pictures of the offending case and primer, it is hard to know everything.

It is a myth that you want the case to "stick" to chamber walls. High friction between the case and chamber will prevent extraction. If you have a very hot round, breech pressures can be so high that the case will still adhere to the chamber during extraction, instead of relaxing from the chamber walls. Most of the times that I have seen high pressure incidents in AR's, a rim gets ripped off. I have seen times where we had to kick the bolt open, and it was due to high pressures. And I would expect to see a pierced primer, blown primer, or leaking primers.

You had a high pressure event of some sort. Funny things happen, your case was not extracted, the bolt did not open up, and you were unable to open the bolt because the case was so firmly stuck in the chamber.

You are lucky that a case head did not blow. That could have blown out the metal around the upper receiver and barrel end., would have blown out the magazine, ruining it (seen that!).

I would not shoot any more of that stuff, I would call the manufacturer and explain what happened, and see if they refund your money for the ammo.

taliv
October 20, 2008, 09:58 AM
ok...

are we saying the previous round was overpressure, blew a primer and stuck the next round in the chamber so it had to be hammered out live? and that the bolt was forward but not in battery so it couldn't be fired?

or

are you saying a round was stuck in the chamber, fired, blew a primer, but not only would not eject, but would not let loose of the extractor so the bolt would not go back either?


-----

in the first case, i don't see how overpressure on a previous round would be enough to cause an in-spec second round to get stuck. and an out-of-spec second round can get stuck all by itself so overpressure on a previous round is probably a separate, unrelated issue.

the second case is what i've never experienced before. I'll try to pick up that issue somewhere.

alsaqr
October 20, 2008, 10:17 AM
Who made the rifle?

KingTiger
October 20, 2008, 03:45 PM
Georgia Arms uses surplus SAW MG brass for their .223 "Canned Heat" reloads. Running it through the SAW apparently stretches the brass and causes problems. My local SOT, who's also an AR armorer, won't shoot it any more since he's personally witnessed several KB's because of their ammo. GA Arms did fix the damages after you can prove it was their ammo causing the problems (one was a M-16 lower). I'll try & find the link w/pictures.

I still shoot it, my RRA likes their 68 gr. BTHP Match, but I don't shoot 1K rounds per month like some do, so my odds of a KB are alot lower.

Rich_Lather
October 20, 2008, 09:09 PM
SAW reloads would explain the kwality of the brass, and perhaps this malfunction.

The case measured 1.757 +-.002 in length. Primer pocket was .183.

These rounds are sold as .223. The rifle is DPMS, first time on the range. They spec the barrel as a 5.56, so if facts are correct, it is the inverse of shooting 5.56 Nato in a .223 spec barrel.

I took it out again today to finish the sight-in. Same ammo, no jams. When I got home and started cleaning it, a primer rolled out of the lower, just like a previous poster mentioned.

I don't think I'll be going to Georgia Arms for .223 again. Their .308 is spot-on and cheap, so I don't want to disparage them entirely.

http://i70.photobucket.com/albums/i119/Rich_Lather/cart1.jpg

http://i70.photobucket.com/albums/i119/Rich_Lather/cart2.jpg

briansmithwins
October 21, 2008, 10:55 AM
Is that brass flow into the ejector I see?

Looks like overpressure to me. BSW

ants
October 21, 2008, 11:56 AM
Yes, that's what one would surmise, BrianSmith.

All the signs are there, aren't they? The expanded pocket, the blown primer, brass flow into the ejector, the ring above the case head, the bolt lugs jammed hard against the barrel extension (that's why he couldn't open the bolt), and everything.

In addition to overcharged cartridge or poorly prepped case, overpressure can also be the result of barrel obstruction. Inspect your bore carefully.

PvtPyle
October 21, 2008, 12:09 PM
They may have been sold as .223, but you can clearly see the NATO cross on the lower left rim. If it was not trimmed to fit the .223 chamber, this is where your problem comes from. And dont slam on them for making a mistake. It happens to the best of companies. I have seen it hundreds of times with bulk MIL and LEO brass.

Now what you need to inspect is the bolt face for any kinds of damage and the hole in the bolt where the bolt cam pin goes for cracking. This is a weak point in the bolt. If they are all good, you should be fine. But you still need to have a set of 5.56 and .223 headspace gauges thrown on it for good measure.

longdayjake
October 21, 2008, 12:55 PM
Here is what I bet happened. Some said that their rounds were fired from a SAW then my explanation would be wrong but here goes. I pick up and reload a ton of police range brass. Most of what I pick up is remington but one day I found a bunch of lc brass. I reloaded the LC thinking that it was better than the remington because everyone seems to love LC. Well, the police must have rifles chambered in .223 because some of the LC brass that I shot had the same issues. I checked them and found that some of the ones that I loaded had oval primer pockets already. So, maybe before Georgia got the brass it had already been fired in the wrong rifle and then reloaded with an already bad primer pocket. Also, the case looks as though it may have been reamed rather than swaged. Sometimes if they ream it too deep the primer doesn't sit tight enough. If this is the case then georgia should probably change their methods. Blown primers are scarry. I was shooting mine the other day and one got stuck in my trigger assembly. All of the sudden I thought my safety turned on. As I am trying to figure out what happened I clear the mag and flip safety on and off with no results. So, I go to Pogo the bullet out and boom. The only thing I can think of is that when I pulled the trigger it released but was stuck by the primer. When I pogoed it the primer popped loose. Had my face been in front of the muzzle...

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