Primer popping

[Akoni]

I have a rifle that somewhat fairly recently started to have issues with primers popping. Other than the ammunition, what can go wrong in an AR that may lead to an increase in popped primers? What parts do I need to check? The only non-colt part on this rifle is the barrel assembly.

[jmart]

I have a rifle that somewhat fairly recently started to have issues with primers popping. Other than the ammunition, what can go wrong in an AR that may lead to an increase in popped primers? What parts do I need to check? The only non-colt part on this rifle is the barrel assembly.

What ammo are you using? M193 spec? Is the chamber a Wylde or NATO chamber or is it commercial .223? If running 193-spec ammo through a commercial chamber you defintely will have primers popping sinces pressures are running much higher.

Primers popping is not good. Your firing pin and bolt face are going to be ruined if you keep it up.

[Akoni]

The suspect ammo is RG surplus SS109. The barrel is "supposed" to have a 5.56 chamber. I know it's not good for the rifle but that's not what I was asking. Other than the ammo, are there things to look at on the rifle that may be a contributor assuming a proper 5.56 chamber?

[jmart]

The suspect ammo is RG surplus SS109. The barrel is "supposed" to have a 5.56 chamber. I know it's not good for the rifle but that's not what I was asking. Other than the ammo, are there things to look at on the rifle that may be a contributor assuming a proper 5.56 chamber?

The only other thing I can think of is to make sure the leade area of your barrel is clean and carbon-free. And even that's a stretch.

I've seen reports within the sporting rifle community that worn leades can over time can contribute to higher pressures in certain circumstances. But those are also powder dependent. Basically you have to have a couple of bad things coming together to get into the high pressure problem.

I'd try switching ammo and see if your problems continue. has this barrel performed acceptably in the past and only now it's popping primers or is it new and exhibiting this from the get go?

[Akoni]

This barrel had about 6k of trouble free performance prior to this issue starting. Most of that was XM855 but it had digested 1k of a different batch of Radway also without a problem. This new batch of RG seems to be implicated in these probs but it works fine in my other rifles. Can the extractor wear to a point where it won't pull the cartridge out of the chamber leaving the spent primer to contain the falling pressure? I've had numerous FTE's since this all began. I was out of extractors but have some new ones on the way.

[jmart]

Can the extractor wear to a point where it won't pull the cartridge out of the chamber leaving the spent primer to contain the falling pressure? I've had numerous FTE's since this all began. I was out of extractors but have some new ones on the way.

No. I believe the reason you are having FTE's is that pressures are way high. The case is stil probably gripping the chamber's walls pretty tightly. If you have heavier weight buffers or a Tubbs CWS insert, you may want to try adding one to delay unlocking a bit, but the case/primer will still see the same high pressure.

Another bad consequence of popping primers is now you have a primer that can lodge in your FCG which can cause all sorts of other mechanical problems. There's an AAR over at 10-8 of a course down in FL where a popped primer lodged somewhere in the cam pin area and the carbine was locked up tight. Like pounding the bastard on the ground without effect tight, like pounding rods through the bore without effect tight. It was a real problem. They eventually got things sorted out but standard clearing protocols were ineffective.

I realize above you know that popping primers isn't a good thing, but it's more than just wear and tear on the bolt. Other bad things can happen. Just something else to consider.

[Robb Jensen]

Ned Christiansen has a 5.56mm neck and throat reamer for this purpose (to eliminate primer popping). I have one, let me know if I can help.

http://www.m-guns.com/tools.php (look half way down the page).

Popping and flattened primers is signs of over pressure. If the chamber isn't a true 5.56mm NATO chamber and can have high pressure spikes, so high that something has to give and the primer is the easiest way out. The Christiansen reamer does a very good job, I did two of my co-workers ARs that were popping primers too. Both were Armalite barrels, after reaming the popping primers stopped.

[cz7]

seen this with win 855 mil-spec not with fn ss-109 in the same ar-15

[-H-]

It sounds like it is an Ammo specific problem.

You said it shoots M855 and a seperate batch of RG with 0 problems.

I'd put my money on it being a bad batch of RG. If it starts happening with American made 5.56 loadings then there is a problem.

[Akoni]

Ned Christiansen has a 5.56mm neck and throat reamer for this purpose (to eliminate primer popping). I have one, let me know if I can help.

http://www.m-guns.com/tools.php (look half way down the page).

Popping and flattened primers is signs of over pressure. If the chamber isn't a true 5.56mm NATO chamber and can have high pressure spikes, so high that something has to give and the primer is the easiest way out. The Christiansen reamer does a very good job, I did two of my co-workers ARs that were popping primers too. Both were Armalite barrels, after reaming the popping primers stopped.

I'm back in country now and need to sort this carbine out. I just installed a new extractor, spring and o-ring. I looked at the chamber/bore closely and it was DIRTY, like big time. It's soaking in all kinds of stuff at this time and it will get a good scrub-a-dub. I'll take it back out this week sometime and give it another run with some anemic ammo and the same can of RG that was giving issues before. See how that goes. I'll also try that RG out in a stock 6920 to see how it runs there.

If this doesn't do it and the RG runs fine in the 6920, I'll have to get a new barrel. What is a good quality mid-length gas barrel (14.5 or 16) that has "all the right stuff"? (4150 or better, chrome chamber/bore, proper 5.56 chamber, F FSB, etc) What about Sabre Defence? Grant, do you stock Sabre barrels?

Will report after I get it to the range.

[Robb Jensen]

The RG will run fine in a 6920 do to the 6920s 5.56mm NATO chamber. As I said running this reamer in a non 5.56mm chamber will cure your pressure problems. Replacing the barrel is the expensive cure, like replacing your car because it needs a tune up. If you need yours reamed with the chamber let me know.

[Akoni]

If you need yours reamed with the chamber let me know.

Thanks. If it doesn't work out, I'll contact you about reaming the chamber. It is supposed to be a 5.56 chamber but it may not be. I hate to lose the chromed chamber which is why I might change the barrel out anyway but it would be interesting to find out whether it is in spec or not. This rifle started as a 6920 (and pretty much is minus the barrel) but I changed the barrel because the original did not shoot anything well which is odd for a Colt.

[Robb Jensen]

Reaming will only remove a small about of chrome from the chamber (at the neck and throat) not the entire chamber. In my experience Colt 5.56mm barrels do not have trouble shooting RG. My wifes 3gun rifle has a Colt 16" .625" chrome chamber but unchromed bore barrel which runs 100% on RG.

This is the description of it from Neds website:

Neck and Throat 5.56 Reamer - (bottom two items in the top image) A common problem when firing 5.56 mil-spec ammo in an AR15 with a SAAMI-spec .223 chamber, is that once in a while a spent primer will fall out of a case as it is extracted. Sometimes the primers fall clear and there's no problem, other times they will go under the trigger and get wedged, rendering the rifle inoperable. We've seen some extreme cases of this where the hammer and trigger were actually hard to get out. We've seen them get wedged between the charging handle and the inside of the receiver, with the bolt out of battery, so that the gun had to have the stock removed so the bolt could be removed to clear the primer. We have seen the primer anvil get stuck on the tubular portion of the carrier key! Popped primers are due in part to the tighter freebore and shorter, more abrupt lead or throat of the .223 chamber, causing a pressure spike with the hotter, mil- spec ammo. This reamer will address these areas as well as making sure the neck diameter is not too tight or short, without changing headspace. It does not cut the shoulder or anything behind it, it stops off on the shoulder. Of course, whatever rifle you're shooting, you could just look at what's stamped on the barrel-- it might say .223, or it might say 5.56, or it might say nothing. You could call the manufacturer and ask them what chamber you have, but even if you get to talk to somebody who understands the question, they likely don't really know. They may tell you what you want to hear, but truth is, not many AR15 manufacturers make their own barrels. They buy them from someone else, so they don't really, truly know what chamber you have. Some of them will flat decline to discuss it with you.

This reamer is designed as an easy, quick and sure way to know. It is provided with an extension T-handle that has a Nylon bushing on it, so you can just open the upper receiver, remove the bolt group, drop it in with some oil, and slowly turn it in (clockwise only, never reversing it), using a lot of turns and very little pressure. The Nylon bushing centers the extension in the upper receiver. When it bottoms out on the shoulder it will spin freely-- it has stopped cutting and you are done. When you have done this, you know for sure you have chamber with proper 5.56 dimensions in the critical freebore and throat area. Primer popping due to pressure spikes in a short lead will cease, but be advised there can be other factors in popped primers such as hot ammo, hot chambers, and improperly loaded ammo.

What about chromed chambers? The good news is that in our experience, Colt AR15 chrome-lined barrels have a proper 5.56 chamber. I would consider any others to be suspect. The reamer has been subjected to a secondary heat-treating process, titanium carbo- nitride, which makes it capable of correcting under-spec chromed chambers. Obviously it will do fewer of them, and I can't say what the numbers would be as I have not had to ream that many chromed ones yet. Will removing the chrome be a problem? No. Plenty of AR's don't have chromed bores and chamber and they work fine. I've sectioned some chromed barrels and the chrome doesn't last long in the throat area anyway. Removing chrome in the chamber won't cause the area to peel like bumper chrome.

[Pat_Rogers]

Ned speaks the truth and has a wealth of knowledge to back it up. Dean Caputo states flatly that when he see's "1/9 NATO" on a barrel, he is immediately suspect. Between the two of them i kinda' think that they are on to something.
My experience is that a great many od the aftermarket makers put out 223 chambers no matter what the barrel is marked. dpms told me over the phone that "everyone wants match chambers", making me realize that their primary customer base is probably 3 gun competitors.
There is precious little chrome in the chamber. Reaming it out w/ Ned's neat tool is a quick and functional solution- that chrome will erode away after a few thousand rounds anyway. It is less expensive then buying a new barrel, but if you go that route, make sure that you buy from someone trustworthy (BCM for example ;) ) who you can trust.

Hot ambient air and harsh firing schedules can cause pressure spikes. Add to that ammo w/ poor QC and a too tight chamber and you will have problems.
Primer cups/ anvils seem to mostly find their way under the trigger, or in the case mentioned above in Lakeland FL, it went into the bolt cam slot, causing a true jam.

[Akoni]

or in the case mentioned above in Lakeland FL, it went into the bolt cam slot, causing a true jam.

Howdy Father Pat, this is me, Mr Lakeland. Anyway, no dice today. I'm now convinced that the chamber is out of spec. That suspect ammo (RG 93) ran through my other 6920, a 6933 and a 5.56 AK today all without a hiccup but it didn't go ten rounds before it popped another primer in the suspect carbine (landed in the barrel extension this time). The spent cases did not show any outward signs of over-press from the other rifles. I'll have to get hold of one of Ned's reamers and try it out. I will in all likelihood replace the barrel anyway, sooner rather than later.

T

[Pat_Rogers]

Brother!
I'm glad that happened at the end of the class...whew!

Barrel makers apparently have a vision of tight chambers=increased accuracy so anything else is nonsense. At least some of them do,
The thing is that a match chamber on a carbine is a lot like a match trigger on a carbine which is a lot like mammaries on the proverbial bull.
The first step is to have a rifle that works, and when the majority of the ammo they are shooting is in the 6-8moa range anyway (never mind the distances are (relatively) close, those chambers/ triggers become superfluous.

[Heavy Metal]

I got a 1/9 carbine standard weight barrel that claims its NATO spec for chamber. I trust these markings...................it came from the land of the prancing pony though:D


Barrel makers apparently have a vision of tight chambers=increased accuracy so anything else is nonsense. At least some of them do,
The thing is that a match chamber on a carbine is a lot like a match trigger on a carbine which is a lot like mammaries on the proverbial bull.

Careful Pat, they will be adding tailfins next. I think some barrel makers are about as common sense impaired as your typical libtard.

Funny thing I read over at the other site yesterday.

Seems some major builder(Vector Arms) ran out of Chromed 7.62 AK barrels. Some in the thread were actually positing the lack of chrome on the domestic barrels would make that AKM a more accurate weapon.

Finding this hypothetical improvement in accuracy will be about as easy as obtaining virtue in a house of ill repute I will wager.

[Pat_Rogers]

I'll have to make sure Dean gets a load of crap about that:p !
I think Ned hit the nail on the head in reference to chambers....

Re the AK barrels. That is funny. Almost as funny when the arms shill stated that the loose mounts were actually "soft mounts" and were designed that way from the factory.

I never fail but to be amazed at the depths some sink to...:rolleyes:

[C4IGrant]

I'm back in country now and need to sort this carbine out. I just installed a new extractor, spring and o-ring. I looked at the chamber/bore closely and it was DIRTY, like big time. It's soaking in all kinds of stuff at this time and it will get a good scrub-a-dub. I'll take it back out this week sometime and give it another run with some anemic ammo and the same can of RG that was giving issues before. See how that goes. I'll also try that RG out in a stock 6920 to see how it runs there.

If this doesn't do it and the RG runs fine in the 6920, I'll have to get a new barrel. What is a good quality mid-length gas barrel (14.5 or 16) that has "all the right stuff"? (4150 or better, chrome chamber/bore, proper 5.56 chamber, F FSB, etc) What about Sabre Defence? Grant, do you stock Sabre barrels?

Will report after I get it to the range.

All out of SD Middy barrels. Do have some Noveske barrels in stock though.


C4

[Akoni]

All out of SD Middy barrels. Do have some Noveske barrels in stock though.


C4

Roger that Grant. I'm going to get the current barrel reamed to spec initially, just for grins really and then will replace it when I decide on what I want. Maybe a Noveske with an FSB or the Sabre. Are you expecting any SD middys anytime soon?

[Derek_Connor]

Just yesterday I had the mother of all jams, I popped a primer on Lake City brass. It slipped its way into the hole for the cam pin and really ruined the shooting session. Temp was approx 75degrees, and it was the 9th round of the shooting session.

I have never seen that happen in person and glad I saw it, but damn do I wish that on no one..

[Robb Jensen]

Just yesterday I had the mother of all jams, I popped a primer on Lake City brass. It slipped its way into the hole for the cam pin and really ruined the shooting session. Temp was approx 75degrees, and it was the 9th round of the shooting session.

I have never seen that happen in person and glad I saw it, but damn do I wish that on no one..

PM me Derek. I'll ream it FREE with Neds 5.56mm NATO neck and throat reamer if you pay return shipping.

[Akoni]

Just wanted to post a bit more on this before I totally disappear. Gotm4 reamed the barrel using Ned's reamer and according to him "it removed very little metal". I got it back and did not have the time to really put the spurs to it before going oconus but did manage to sneak in ~200 rds of the Radway Green that was causing problems in this rifle. No primers popped in the limited test....that's an improvement. I did however have 2 FTE's towards the beginning of the session. Still not sure why this lot of RG causes so many problems in this rifle but not in others. I hope to do a more extensive test later this year.

[Ned Christiansen]

Akoni, I don't think I ever saw in this thread, what brand was the barrel? After 6K rounds one would think things'd be washed out to where they need to be but sometimes you still get a fair amount of chips..... sounds like not in your case..... I don't get too surprised one way or the other any more.

I am a little surprised though that Radway Green ammo was popping primers, since everything I hear, and my limited personal experience with it, is that it is rather mild stuff. But there are so very many variables.

[Akoni]

Akoni, I don't think I ever saw in this thread, what brand was the barrel? After 6K rounds one would think things'd be washed out to where they need to be but sometimes you still get a fair amount of chips..... sounds like not in your case..... I don't get too surprised one way or the other any more.

I am a little surprised though that Radway Green ammo was popping primers, since everything I hear, and my limited personal experience with it, is that it is rather mild stuff. But there are so very many variables.

Ned, the barrel is from the first batch of 16" mid-length gas, chrome lined barrels that I had ever seen for sale anywhere. They were from a group buy on TOS (long time ago). I believe they were done by CMMG.

I too am surprised that the RG was popping primers since that vintage RG is supposed to be a bit anemic.