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Old February 6, 2014, 04:42 PM   #26
thallub
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In 1968 my .222 Sako was rechambered to .223. Since then i have fired many hundreds of thousands of 5.56mm rounds in my bolt action .223 rifles. There has never been a popped primer. My last 10-12 re-barrel jobs were accomplished by my machinist son using my .223 reamer.

The problem is often an out of spec or tight chamber. Few chambers of factory rifles are reamed by gunsmiths or machinists; you get whatever chamber the laborer happens to give you.

Some of the US made 5.56mm ammo being sold today has been rejected by the US Army. i have found .223/5.56mm cases with necks that were .015 longer than spec. Jam the case mouth into the leade and pressure rises dramatically.

There are a plethora of various .223/5.56mm chambers. Click: Detailed 223 vs. 5.56 reamer dimensions comparison showing different variations:

http://ar15barrels.com/tech.shtml
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Old February 7, 2014, 01:00 AM   #27
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...based on the available evidence, what say you?
One point of view is put forth by published information from Patrick Sweeney, Glen Zediker, SAAMI, Winchester, Hornady, Fulton Armory, Walter Kuleck and supported by additional information from independent sources indicating that what the experts predicted could happen, did happen in some cases when the ill-advised action was taken.

The other is supported by personal anecdotal evidence (of the "I've done it and gotten away with it so far." variety) and by an article written by luckygunner (A source, by the way, who clearly states that he has seen firing 5.56 in a .223 chamber exhibit pressure signs.).

I don't know--let me think about it for awhile...
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Old February 7, 2014, 11:08 AM   #28
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Appeal to authority is the weakest argument

But specifically I was asking whether you thought the popped primers was a result of a secondary pressure spike or not.

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Old February 7, 2014, 11:56 AM   #29
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Does anyone here find it strange that SAAMI waited until huge quantities of surplus 5.56mm ammo hit the market to send out their dire warnings?

Would SAAMI lie to you? Yes, SAAMI would lie to you. SAAMI has lied before. Without consulting ammo manufacturers, SAAMI asked OSHA to re-write the rules for ammo storage and transportation: OSHA did just that. Ammo companies and others raised holy hades when the new reg came out for comments. SAAMI jumped on the internet and lied about their involvement, enlisted the help of gun rights organizations and appealed to gunowners to write to OSHA.

http://www.thehighroad.org/archive/i...-285452.html&&

Yep, SAAMI also tells us that military brass is thicker than commercial brass.
Click on 223 Brass Weights Comparison:

http://ar15barrels.com/tech.shtml


Bottom line: If you think that firing 5.56mm ammo in .223 chambers is dangerous then don't do it.

As for me, i still have a few hundred thousand 5.56mm rounds that cost me little or nothing.
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Old February 7, 2014, 11:15 PM   #30
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Appeal to authority is the weakest argument.
The logical fallacy of appeal to authority is when a person uses the views of an authority to support his own when the authority is not an expert on the topic at hand. Like quoting Einstein's political views to support one's own political views although Einstein was a physicist, not any sort of expert on politics.

http://www.nizkor.org/features/falla...authority.html
http://www.csun.edu/~dgw61315/fallac...%20verecundiam

That said, even the fact that an authority who is an expert on the topic at hand, says something does not automatically make it true. It would be a weak argument, therefore, to use the statement of a single authority to attempt to validate one's opinion or position.

That's hardly what is going on here.

1. I didn't cite a single authority, I listed a number of them. Again, that's not solid proof, but it carries significantly more weight than it would if there were only one expert on the issue who agreed.

2. The authorities I cited, in general, haven't simply voiced an opinion on the topic, they have provided reasonable explanations of why the mismatch is a bad idea and how it can cause problems. So it's not just that we are expected to rely on stated opinions, we also have explanations which we can see to be consistent with the general principles of internal ballistics.

3. The authorities I cited are all firearm/ammunition experts, not experts in some unrelated field.
Quote:
But specifically I was asking whether you thought the popped primers was a result of a secondary pressure spike or not.
It seems kind of unlikely given the one article's comments about the barrel length required for a really high secondary pressure spike to occur. But who knows--it could be responsible for some of them.
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Yes, SAAMI would lie to you. SAAMI has lied before.
1. The fact that they have lied before doesn't automatically mean they're lying about this issue.

2. Even if we were to completely discredit SAAMI, there's still a formidable list of authorities and experts who agree on this topic, and it doesn't eliminate the factual basis for their stated position.
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As for me, i still have a few hundred thousand 5.56mm rounds that cost me little or nothing.
And that's the crux of this issue, isn't it.

The OP, first asked this question some 2 years ago on another forum and was given a clear answer then. He's asking again for the same reason you're giving for ignoring the warning. It's not really because the facts are in question, it's because people feel they have a strong incentive to ignore the warnings.

For what it's worth, if you have been shooting that ammunition in your gun without incident, the odds are very good that continuing to shoot it in the same gun will be similarly incident free as long as you don't signficantly alter the circumstances under which you are shooting the ammunition.
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Old February 8, 2014, 12:57 AM   #31
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JohnSKa,

Glen Zediker's article on chambers mentions a 15k increase in pressure, specifically dealing with long match bullets and he quotes another source for his pressure data. From 55k to 70k is still less than a proof load and not enough to pop primers. Patrick Sweeney's article says that most of the "5.56 ammo you buy isn't really 5.56 ammo." and he quotes another source for his pressure data. Walter Kuleck doesn't quote any pressure data, simply states again the difference in leade and notes that Win White Box offered two versions of 55gr bullets, one loaded in America, the other from Israel.

The only people providing actual pressure data have already been listed on this thread. Appealing to experts who are relying on other experts is at best secondhand expertise.

In a similar vein to the Win White Box dilemma:
Look at these advertisements for American Eagle 55gr loads.

From midwayusa a 223 load: http://www.midwayusa.com/product/953...cket-boat-tail

55gr at 3240 fps. Peak pressure not listed.

From CTD, an XM193 "milspec" load: http://www.cheaperthandirt.com/product/AMM-269

55gr at 3165 fps. Peak pressure 55k at the case neck.

Now 75 fps could be as simple as different barrel lengths. Or it could be that they were loaded with different powders. Or it could be that the "milspec" load is perfectly safe for an AR-15 with a 223 Rem chamber, which is why Winchester had no problem milspec milspec M193.

The experts agree that sometimes you get a popped primer with a 223 chamber shooting "5.56" spec'd ammo, although at least one guy reported a popped primer with a 223 pressure load in a 5.56 chamber http://www.ar15.com/forums/t_3_16/60..._up_ar15_.html . Secondly, there is a lot of "this could happen" type reasoning going on which leads me to believe that we don't know exactly what is going on.

So based on what I actually know based on available data, I would rate the most important to least important factors as powder, pressure, brass, chamber in that order. I know for a fact that a 55gr FMJ in any chamber out there isn't jammed into the lands, not even a SAAMI minimum chamber, so it seems more likely that something else is more important, like an ingnition delay (primer goes off, pushes bullet into lands, powder has a delay in building pressure but is now locked into the brass by a stuck bullet) or a Secondary Pressure Spike.

Either way, I'm still curious as to the actual mechanics of an overpressure event that pops primers.

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Old February 8, 2014, 10:00 AM   #32
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Yep, It's easy. If you are convinced it's dangerous, simply do not shoot 5.56mm ammo in .223 chambers.
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Old February 8, 2014, 03:33 PM   #33
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jmr40
It is possible that SOME military 5.56 ammo is loaded slightly hotter than SOME 223 ammo.
I have seen 55 gr Malaysian surplus 5.56mm clock 3300 fps over the chrono with a 14" barrel.
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Old February 8, 2014, 04:06 PM   #34
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I had never experienced any problem shooting 5.56 out of a .223. This was limited to Remingtons, Savages and Winchesters firing Lake City 193 and 855. Sure, I read the "don't shoot 5.56 out of .223" but I'd ignored it.

...and I still ignore it for the most part.

A few years back Bushmaster built a batch of AR rifles marked .223. I ignored it.

Here are the results. On the left is Lake City 855 fired from the Bushmaster. On the Right is the same ammunition fired from a Colt 601.

A few minutes with a 5.56 chamber reamer and no more blown primers.

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Old February 8, 2014, 07:22 PM   #35
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The vast majority of popped primers happen with AR-15 rifles. i've never heard of a popped primer when firing factory .223 or 5.56mm ammo in a bolt action rifle. Prior to about ten years ago i never heard of a popped primer when firing an AR-15. Now it's more or less an accepted fact: That is bad.

i own two old Colt AR-15 rifles that were made before 1970. Neither has ever given any signs of high pressure when firing 5.56mm military M193 ball ammo. Neither has my Remington model 760. All my 5.56mm ammo is dated 1980 and prior. i would refuse to fire much of the 5.56mm ball ammo being sold today.

Most AR-15 rifles that experience popped primers are relatively new. The AR-15 is the most popular gun sold in this country. Companies we never heard of five years ago are building AR-15 rifles. Some of those companies use unskilled labor to ream chambers. It's a race to the bottom to build cheaper guns: Cheap guns require cheap labor.

Two gunsmiths have told me no manfacturer chambers .223 guns to SAAMI specs. Very few AR-15 manufacturers belong to SAAMI:

http://www.saami.org/member_companies/index.cfm

i know for a fact that some of the ball ammunition being sold today has been rejected by the US military. The US military uses very little M193 ball ammo. But untold millions of rounds are being purchased for foreign countries. Army QUASAS folks test that ammo and either accept or reject same.

Who knows why the ammo you get was rejected. Maybe the velocity was too low. Maybe, just maybe; the lot of ammo you get was rejected because the firing pressure was too high or the cartridge case was out of spec.

i've already addressed the fact that some .223/5.56mm ammo being sold today has long case necks. As much as .015 too long.
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Old February 8, 2014, 08:40 PM   #36
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From 55k to 70k is still less than a proof load and not enough to pop primers.
Assuming that we accept that a 15Kpsi pressure increase won't pop primers, that's a reasonable point in terms of explaining why the primers pop. But it's absolutely not justification for ignoring the mismatch warnings. 70K is within 3% of being a proof load for the .223, and it's obviously well over SAAMI max for the caliber.

Furthermore, if you add in another factor (such as warm weather), then you do get to the point where the two factors, together, can provide exactly the reported result.
Quote:
Patrick Sweeney's article says that most of the "5.56 ammo you buy isn't really 5.56 ammo."
Again, that's an interesting point, but it doesn't speak to the real issue. That is more evidence as to why it's not common for people to see a problem with this issue. We already know that not all .223 guns have .223 chambers. Now we find that not all 5.56 ammo is really 5.56 ammo.

But that doesn't change the fact that when you DO end up with REAL 5.56 ammo and a REAL .223 chamber, the mismatch can drive pressures up well above SAAMI max. And that it can, under certain circumstances result in blown primers and potentially other issues.

So do we tell people that they should ignore the warnings because they might not have a real .223 chamber or might not have real 5.56 ammo? Unless we can tell them how to know for sure what kind of chamber and ammo they have, it would be irresponsible to make such a recommendation.
Quote:
The only people providing actual pressure data have already been listed on this thread.
Given that I listed sources like Winchester, Hornady, and SAAMI, that assertion is not remotely credible. Clearly ammunition makers and ammunition standards organizations have access to "actual pressure data".

Even if you want to dismiss all the other sources, I don't see how you're going to be able to make the case that Winchester and Hornady are simply relying on other experts when they provide the mismatch warning.
Quote:
Secondly, there is a lot of "this could happen" type reasoning going on which leads me to believe that we don't know exactly what is going on.
Even your primary source (luckygunner) doesn't advise ignoring the mismatch warning, stating that his advice is to buy whatever chamber fits your needs and then avoid the mismatch. He also provides pressure data showing that some of his 5.56 testing in .223 chambers showed pressures over SAAMI max.

Maybe we don't know EXACTLY what's going on, but the basics (i.e. the mismatch can cause overpressure discharges) don't seem to be in dispute.
Quote:
Here are the results. On the left is Lake City 855 fired from the Bushmaster. On the Right is the same ammunition fired from a Colt 601.

A few minutes with a 5.56 chamber reamer and no more blown primers.
So, trigger643, how can you explain the fact that reaming the chamber to 5.56 dimensions eliminated the secondary pressure spike? (Ok, I kid.)

Thanks for posting your results.

Chamber/Ammo Mismatch=blown primers
Eliminate the mismatch by reaming the chamber and then retest using the same ammunition and firearms=no blown primers.

That should be conclusive.
Quote:
i've never heard of a popped primer when firing factory .223 or 5.56mm ammo in a bolt action rifle.
I have heard of a few instances where shooters reported difficulty opening the bolt after shooting 5.56 in a .223 bolt rifle.
Quote:
The vast majority of popped primers happen with AR-15 rifles.
Which is a good reason to discount the secondary pressure spike as a mechanism given that it is not supposed to occur in barrels of 20" or shorter.
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If you are convinced it's dangerous, simply do not shoot 5.56mm ammo in .223 chambers.
The issue here is making sure that others who haven't already made up their mind can get a clear view of the big picture so they have a chance of making an educated decision.
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Old February 8, 2014, 08:58 PM   #37
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I have never had a problem shooting MILSPEC / USGI 5.56 through any commercial .223 chambered rifle. And I have shot a lot of it.

Regards,

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Old February 11, 2014, 01:27 AM   #38
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New to the AR (have 1 and working on my .458 socom build) and reloading, but isn't the 5.56 reloading data the same as the .223?
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Old February 11, 2014, 11:01 AM   #39
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Again, that's an interesting point, but it doesn't speak to the real issue. That is more evidence as to why it's not common for people to see a problem with this issue. We already know that not all .223 guns have .223 chambers. Now we find that not all 5.56 ammo is really 5.56 ammo.

But that doesn't change the fact that when you DO end up with REAL 5.56 ammo and a REAL .223 chamber, the mismatch can drive pressures up well above SAAMI max. And that it can, under certain circumstances result in blown primers and potentially other issues.

So do we tell people that they should ignore the warnings because they might not have a real .223 chamber or might not have real 5.56 ammo? Unless we can tell them how to know for sure what kind of chamber and ammo they have, it would be irresponsible to make such a recommendation.
JohnSKa,

I'm not disagreeing with anyone about some "real issue" I'm asking "why does this happen and what is the mechanism." You say that all those manufacturers and industry groups are credible sources, so please show me their data. If you can't show me their data then you can't prove their are credible and you are have no idea about sample size, testing methodology, or exactly what they experienced to come to their conclusion. Without access to that data those organizations have nothing to add to the "why" part of the discussion.

I think that the "popped primers" issue with ARs is a sign that of a secondary pressure spike during extraction, although in Trigger643's case it was most likely an ignition delay problem going to a stopped bore situation causing a primary pressure strike. Can't tell with any higher certainty without miking the case heads, but a longer throat would give the bullet further to travel on an initial primer explosion without getting jammed into the lands before the powder could build pressure. It could also have been a primary jam where the case neck got jammed into the throat and caused a mechanical lock on the bullet leading to an overpressure event.

It is one thing to say, "I had this experience, then reamed my chamber, and haven't repeated the experience" and it is a completely different thing to understand what was actually happening with the pressure curves during the firing cycle.

In a bolt action rifle with 223 chambers firing 5.56 pressure ammo, we don't see popped primers, we see cratered and sometimes pierced primers. This indicates to me that at least some of the popped primers in AR's due to the primer not being fully supported, indicating that a high pressure event is happening in the brass while extraction is taking place. This to me indicates a secondary pressure spike (even one less than 70k, as it doesn't take much pressure to push a primer out of the pocket).

The easiest way to test this is to change out the powder in some of those 5.56 loads away from WC844 to a different powder at "max" charge to see if the problems go away. Then again, M193 was spec'd with 28gr of WC844 (unkown actual burn rate) and a velocity of 3250 fps. Load data for H335 (cannister grade WC844) maxes out at under the "milspec" reference load of 28 grains.

However, http://www.thehighroad.org/archive/i.../t-303359.html even 28 grains of H335 should not expand the case head or pop the primers. It is a "hot load" for a 223 but the Ruger #1 used in Clark's test doesn't extract the brass under pressure, also I have no idea where that rifle falls in the range of commercial 223 chambers. Anyways WC844/H335 has known ignition delay issues, so that explains the cratered/pierced primers in bolt action rifles.

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Old February 11, 2014, 11:21 PM   #40
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The powder used in early M193 5.56mm ammo is IMR 4475. The US Army made the change to WC846. WC846 gave the M16 rifle a bad reputation. It increased the cyclic rate of the M16 rifle by 200 rounds per minute.

The M193 round was accepted into the US military inventory with IMR 4475 powder. Then the change was made to WC846, then to IMR 8208.

i sometimes use WC846 for my .223/5.56mm reloads: Mostly because i bought it cheap years ago. Got to be careful with WC846 maximum loads in hot weather. i have some reloads marked for winter use only.

Slightly off topic.
The Ichord committee report on the M16 rifle and it's ammo problems:

http://www.bobcat.ws/rifle.shtml
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Old February 12, 2014, 12:13 AM   #41
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I'm not disagreeing with anyone about some "real issue"...
I can't really tell if you're saying that there is not an issue or if you're agreeing that there is an issue but saying that you disagree with the explanations provided.
Quote:
You say that all those manufacturers and industry groups are credible sources, so please show me their data. If you can't show me their data then you can't prove their are credible...
Are you saying that ammunition makers and industry standard groups don't understand why the mismatch is a bad idea? Are you saying that they know why but have agreed to conspire to provide an false explanation for why the mismatch is ill-advised? Are you saying that they all independently came up with the same wrong explanation for why the mismatch causes issues? What is is that you disagree with and what is it that you claim?

I don't really understand why you're calling their credibility into question in the first place in spite of the fact that you haven't presented any evidence that disproves any of their claims.

You have provided some alternate explanations for the issues that arise, some of which might make sense, some of which don't appear to be relevant given the other information available. But providing an alternate explanation/mechanism for an occurrence isn't the same as disproving the accepted explanation/mechanism.
Quote:
at least some of the popped primers in AR's due to the primer not being fully supported, indicating that a high pressure event is happening in the brass while extraction is taking place. This to me indicates a secondary pressure spike...
Your own quoted source states that secondary pressure spikes shouldn't occur in barrels 20 inches or shorter. Are you saying that you don't believe that piece of information from your source but want to still take the rest of the information from that same source as gospel?

Frankly, it looks to me like you're arbitrarily selecting and discarding information based on person pet theories--the only common theme of which that I can see is that they disagree with the mainstream explanation.
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Old February 12, 2014, 01:33 AM   #42
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The one thing that still confuses me is .

Are we talking about factory ammo or are we talking about ammo in general .

The reason I ask is . For those of us that reload . Pull out any of your manuals that have both 223 Rem bolt data and AR 5.56 data . Now compare apples to apple . Meaning check out the loads that use the same bullets and powders . What do you see as far as max loads for each of those chambering .

What I see in both my Hornady and Sierra books is the 223 is loaded to at least the same max powder charges and many times the 223 will allow a heavier charge then the 5.56 . This is something I have just noticed as of late because I started loading for both 223 Remington for a CZ and 5.56 for my AR .

It seems odd to me that you can put equal charges in a 223 and often can put a heavier charge in the 233 Rem then the 5.56 . Am I missing something here ? More powder means more pressure , Yes?

So back to my first point . Are we talking about factory ammo that is loaded to a different spec then what are books are giving us ?

OK I'm sure the books are on the low end when it comes to there max loads . How ever would that not be an across the board thing . Meaning if there 5.56 load data is on the low side . I would think the 223 load data would be on the low side as well giving them a wash and still showing that you can put a heavier charge in a 223 .

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Old February 12, 2014, 10:05 AM   #43
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Are you saying that ammunition makers and industry standard groups don't understand why the mismatch is a bad idea? Are you saying that they know why but have agreed to conspire to provide an false explanation for why the mismatch is ill-advised? Are you saying that they all independently came up with the same wrong explanation for why the mismatch causes issues? What is is that you disagree with and what is it that you claim?
What causes the overpressure, is it the chamber, ignition delay, secondary pressure spike, or some combination? Why do we sometimes see popped primers in 5.56 chambers with 5.56 ammo made by Radway Green? No mismatch there, but the same symptom as if there was a mismatch?

Quote:
I don't really understand why you're calling their credibility into question in the first place in spite of the fact that you haven't presented any evidence that disproves any of their claims.
No, I said you couldn't prove credibility and that without access to their data we don't see what they saw. Was it ignition delay, secondary pressure spike, etc. We can't talk about their data because we don't have their data to see where the pressure mismatch came in the firing cycle. So to say that the blame lies with the chamber when we have good data that 5.56 ammo in 5.56 chambers experiences ignition delays and secondary pressure spikes, and in the case of Radway Green pops primers, it adds nothing to understanding the problem.

Quote:
You have provided some alternate explanations for the issues that arise, some of which might make sense, some of which don't appear to be relevant given the other information available. But providing an alternate explanation/mechanism for an occurrence isn't the same as disproving the accepted explanation/mechanism.
In my experience, if it is a chamber problem then the issue shows up every time you pull the trigger. Excess headspace shows up every time you pull the trigger with factory ammo, tight neck issues show up every time you pull the trigger with factory ammo. So that "this CAN happen" doesn't indicate to me, based on the evidence available to me without having to take any experts word on the matter who won't share data with me.

Having processed and trimmed thousands of Lake City 5.56 brass I know that the neck lengths after full length resizing range from under SAAMI minimum to over SAAMI maximum. A long neck that creates a mechanical lock will cause a serious pressure spike, and I expect at least a blown primer and expanded case head from that event. With WC844 and WC846 there are known ignition delays as reported by DTIC. And there are known secondary pressure spikes with 5.56 ammo even in 5.56 chambers.

And we have seen that 5.56 ammo can pop primers even in 5.56 chambers. If we can't blame that issue on a 223 Rem chamber, what is the problem?

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Old February 12, 2014, 11:23 AM   #44
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I'm not going to get on this "beating a dead horse" band wagon but I want to mention blown primers a bit.

Blown primers may or may not have anything to do with pressure. If you suspect excessive pressure look at the stamping on the rear of the case. It the writing or stampings are deform, it's probably high pressure. If the lettering is sharp and clear, its not high pressure regardless if primers are blown or not.

Take an primed, empty 38 case an stick it in your revolver. Shoot it, you'll see the primer will back out often jamming the cylinder.

Low pressure will can also cause primers to back out. Research "high pressure signs" and study them.
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Old February 12, 2014, 11:38 PM   #45
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In my experience, if it is a chamber problem then the issue shows up every time you pull the trigger. Excess headspace shows up every time you pull the trigger with factory ammo, tight neck issues show up every time you pull the trigger with factory ammo. So that "this CAN happen" doesn't indicate to me, based on the evidence available to me without having to take any experts word on the matter who won't share data with me.
The uncertainty isn't nearly as much as to whether or not it will happen if the mismatch occurs, the uncertainty is whether or not there really is a mismatch in the specific case in question. As has been amply explained and repeatedly mentioned on this thread, some .223 chambers aren't really .223 chambers, and some 5.56 ammo isn't really 5.56 ammo. So there's a lot of "it CAN happen" involved because it's not really at all easy to tell if there's an actual mismatch in the first place.
Quote:
And we have seen that 5.56 ammo can pop primers even in 5.56 chambers.
1. If you're talking about the luckygunner article, he explains that the specific "5.56" chamber he mentioned in that context was badly formed and he described it as "not really a 5.56 chamber".

2. There certainly has been, in the history of 5.56 ammunition, some 5.56 ammunition that was overpressure or otherwise defective. There have certainly been guns with improperly formed 5.56 chambers in the history of 5.56 guns. The fact that there have sometimes been problems with 5.56 ammunition in 5.56 chambers is not evidence that there's no mismatch issue. It's just evidence of the fact that guns and ammunition aren't always defect free.
Quote:
What causes the overpressure, is it the chamber, ignition delay, secondary pressure spike, or some combination?
Again, I come back to the observation that you seem to be working hard to come up with any possible way to explain the problem short of accepting the one that is most obvious, and the one that the experts, standards organizations and ammunition companies give us.

Ok, so you don't like the data from those folks. Luckygunner's pressure data shows that shooting 5.56 ammo in a .223 chamber results in pressures over SAAMI max when shooting .223 in the same chamber does not--look at the pressure data curves provided in his article. Look at his wrapup--he advises against the mismatch.

Basically, everyone who has any access to pressure data agrees that the mismatch should be avoided and provides a similar explanation of why that is true.
Quote:
No, I said you couldn't prove credibility and that without access to their data we don't see what they saw.
Again, what is it that you're claiming? Are you claiming that these organizations and individuals have conspired to deceive the shooting public about the cause of the problems that can be encountered when the mismatch occurs? Are you claiming that they don't know what they're talking about but have all somehow hit upon the same way to explain what they don't understand?

You're seem to be concerned with their credibility, but there doesn't seem to be any real evidence calling that credibility into question. I think that most would agree it's a bit backward to start off the assumption that Winchester, Hornady and SAAMI need to prove their credibility when it comes to ammunition and pressure and that until they do we must accept anyone's proposed theory as having the same weight (or more weight) than the explanations these organizations provide.
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Old February 13, 2014, 09:56 AM   #46
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JohnSKa,

I'm not advocating for a mismatch. Lets just lay that strawman aside ok? I want to know why this issue doesn't show up with every pull of the trigger when there is a mismatch, and sometimes when there isn't a mismatch. If if was the chamber, it should show up every time you pull the trigger. If it doesn't show up every time you pull the trigger, then odds are it is something with the ammo. Can you fault that line of logic?

Quote:
Again, I come back to the observation that you seem to be working hard to come up with any possible way to explain the problem short of accepting the one that is most obvious, and the one that the experts, standards organizations and ammunition companies give us.

Ok, so you don't like the data from those folks. Luckygunner's pressure data shows that shooting 5.56 ammo in a .223 chamber results in pressures over SAAMI max when shooting .223 in the same chamber does not--look at the pressure data curves provided in his article. Look at his wrapup--he advises against the mismatch.

Basically, everyone who has any access to pressure data agrees that the mismatch should be avoided and provides a similar explanation of why that is true.
Ok, so explain to me why the mismatch doesn't cause a popped primer EVERY time if it is really a chamber issue.

The chamber pressure data shown was higher than SAAMI spec, not disagreeing with that at all, simply pointing out that it takes something different than the measured pressures we've seen to pop a primer back out of a pocket.

Quote:
Basically, everyone who has any access to pressure data agrees that the mismatch should be avoided and provides a similar explanation of why that is true.
Except that similar explanation doesn't explain why Radway Green has been known to pop primers even in 5.56 chambers. The exception proofs the rule, meaning that the "similar explanation" is insufficient to explain all occurences of popped primers in ARs.

And the ones that show the pressure trace data, luckygunner and shootingsoftware.com, show some very interesting results, even using 5.56 data in 5.56 chambers, which would explain why we occaisionally see popped primers even when there is no mismatch between ammo and chamber.

Quote:
You're seem to be concerned with their credibility, but there doesn't seem to be any real evidence calling that credibility into question. I think that most would agree it's a bit backward to start off the assumption that Winchester, Hornady and SAAMI need to prove their credibility when it comes to ammunition and pressure and that until they do we must accept anyone's proposed theory as having the same weight (or more weight) than the explanations these organizations provide.
I don't know if you read research journals, but having access to research data is important into weighting the relevance of conclusions drawn. I'm not saying that there is a grand conspiracy to sell more 223 ammunition, so let that strawman drop too. When you don't have access to data and methodology, you can't really evaluate what is going on. For example look up the ALLHAT trial and understand that all the drugs in the trial were shown to be better than placebo, but until ALLHAT those drugs had never been evaluated against each other to determine the most effective course of treatment for hyptertension. Every drug going into that trial had FDA approval and had good data showing that the drug was effective, but until the data was directly compared across drug classes physicians had no idea what would be an optimal treatment regiment.

Or take a look at Michael Mann, still refusing to share his temperature proxy data and methodology so that others can see if they draw the same conclusion. Or the infamous "tin can" ammo that had cold weld issues leading to unsafe pressures, that the Army blamed on competitors greasing their bullets. Was it the ammo or was it the grease?

So I'm not saying that SAAMI, Hornady, Winchester, et all are not credible, I'm saying that we can't prove it for the purposes of this discussion since we don't have access to their data. You can say that they deserve your trust all you want, that is simply not good scientific practice.

Heck, even the scientific debates on whether DNA was conservative, semi-conservative, or non-conservative were all over the board until some researchers got smart and used nitrogen isotopes, e-coli, and a centrifuge to show that DNA is conservative.

Jimro
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Old February 13, 2014, 01:14 PM   #47
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The M16 rifle experienced very rare popped primers almost from the day it was adopted by the US military. It happened with IMR powder as well as Winchester ball powder.

Methinks popped primers in rifles properly chambered for 5.56mm ammo may be related to high port pressure, perhaps in combination with heat soaked ammo or hot ambient temperature. i can tell you that popped primers are a frequent occurrence and that many shooters blow it off. About every fifth trip to the range i see an AR-15 pop a primer.

It's not unusual to see AR-15 owners shoot 200 or 300 rounds in an hour or less. i've seen guys fire three or more 30 round magazines fast as the trigger could be pulled. That gun gets very hot.
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Old February 13, 2014, 10:47 PM   #48
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Quote:
If if was the chamber, it should show up every time you pull the trigger. If it doesn't show up every time you pull the trigger, then odds are it is something with the ammo. Can you fault that line of logic?
Yes I can. If the pressure increase puts the peak pressure right at, or very near the limit for popped primers, then the pressure variations from one shot to the next that are evident in any pressure curve data could easily result in popped primers some shots (or maybe even only once out of a number of shots) but not every shot.

The comments by Sweeney regarding his experience with the mismatch strongly support the idea that the pressure rises aren't super-dramatic. He states that he doesn't usually see issues unless there is another contributing factor--such as high ambient temperatures. That sounds like exactly the scenario I laid out in the paragraph above. The mismatch pushes the pressures up near the threshold limit for problems, and if you get one round that's a little hotter than rest, or slightly oversized compared to the rest, or has the bullet seated out just a tiny bit farther than the rest, or one that hits the chamber when the barrel/chamber temp is hotter than it was for the previous rounds, that one pops a primer while the others don't.

Any pressure curve data will show that the pressure peaks can vary significantly from one shot to the next. It's quite common to see that one of the tested shots will show a significantly higher peak than the others.
Quote:
The exception proofs the rule, meaning that the "similar explanation" is insufficient to explain all occurences of popped primers in ARs.
Why must there be one single explanation for all the incidents of popped primers? There's no logical reason to impose that criteria. I don't see anyone trying to claim that every popped primer in an AR is due to a chamber mismatch. There could be any number of reasons that might cause a primer to pop in any particular gun or with any particular ammo, and none those reasons would invalidate a claim that the mismatch could be one additional cause.
Quote:
...having access to research data is important into weighting the relevance of conclusions drawn.
That's an issue when there's a realistic/reasonable concern that research data might be falsified, in error, or misrepresented or when there's some reason to assume that all the entities providing results might be colluding with each other to deceive. The fact that we have multiple organizations (all of which have access to, and the ability to generate, their own independent research data) providing the same warning and explanation should go a very long way to assuaging fears that the warnings are the result of one rogue organization is making stuff up, or is confused about the basics of internal ballistics.

That's unless there's some credible reason for us to assume that all the organizations are conspiring to deceive the shooting public. That's why I keep asking the question.
Quote:
Or take a look at Michael Mann, still refusing to share his temperature proxy data and methodology...
SAAMI doesn't have to rely on Winchester or Hornady for pressure data. Hornady doesn't need to beg pressure data from SAAMI or Winchester. Winchester can generate their own pressure data. Your examples make it sound like we're at the mercy of a single entity who won't share their data and who is making claims that other authorities contradict.

In fact, that's not even remotely close to what's happening here. No authorities are contradicting the warnings or explanations provided, and we don't have to rely on just one organization, or one organization's conclusions.
Quote:
You can say that they deserve your trust all you want, that is simply not good scientific practice.
I'm not saying that they deserve trust, I'm saying that given that we have multiple, independent sources repeating the same experiment and providing the same warning and explanation, good scientific practice suggests that some sort of credible evidence is required to call the facts into question.

That's why I keep asking what credible evidence you have (and pointing out that none has so far been provided) to call their conclusions into question.
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Old February 14, 2014, 11:24 AM   #49
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JohnSKa,

Quote:
That's why I keep asking what credible evidence you have (and pointing out that none has so far been provided) to call their conclusions into question.
Please list those conclusions, because the only conclusion ever given is "using 5.56 in a 223 chamber can cause a dangerous pressure spike." Please tell me where in the firing cycle the pressure occurs. Tell me the timing of when the primer is ejected. Please don't say, "Well a mismatch causes increased pressures that lead to popped primers" because that doesn't answer the mail about what I want to know. We've already agreed that using 5.56 ammo in a 223 chamber can lead to increased pressures which will pop primers, but we don't know WHEN that happens, primary or secondary pressure spike, or whether an ignition delay is a culprit.

This is the conclusion you have. You don't have conclusions plural.

Quote:
The mismatch pushes the pressures up near the threshold limit for problems, and if you get one round that's a little hotter than rest, or slightly oversized compared to the rest, or has the bullet seated out just a tiny bit farther than the rest, or one that hits the chamber when the barrel/chamber temp is hotter than it was for the previous rounds, that one pops a primer while the others don't.
But I think I'm getting through to you because you also wrote:

Quote:
Why must there be one single explanation for all the incidents of popped primers? There's no logical reason to impose that criteria. I don't see anyone trying to claim that every popped primer in an AR is due to a chamber mismatch. There could be any number of reasons that might cause a primer to pop in any particular gun or with any particular ammo, and none those reasons would invalidate a claim that the mismatch could be one additional cause
.

Which is good because every claim so far about a popped primer in a 223/5.56 gun has been blamed on an ammo/chamber mismatch.

I'm not saying a mismatch doesn't exist, I'm trying to figure out where in the firing cycle that pressure takes place. I believe that if it were a mainly a chamber issue we would see it on the primary pressure peak, and popping primers would be much more consistent.

The reason why pressure trace data is important is that it shows WHERE the pressure happens in the cycle. If it happens on the first peak (the peak that industry normally measures and then stops) then clearly we can blame it on a chamber mismatch. If it happens on the second peak (the only data we've been able to get from that is from the lucky gunner article and shootingsoftware.com) then the bullet is already far down the bore or beyond the muzzle (as in the case of the 7mm STW trace at shootingsoftware.com) when a secondary pressure spike hits, then it ISN'T THE CHAMBER.

I've already written how a more generous chamber could minimize pressure issues due to ignition delay.

Quote:
The comments by Sweeney regarding his experience with the mismatch strongly support the idea that the pressure rises aren't super-dramatic. He states that he doesn't usually see issues unless there is another contributing factor--such as high ambient temperatures. That sounds like exactly the scenario I laid out in the paragraph above. The mismatch pushes the pressures up near the threshold limit for problems, and if you get one round that's a little hotter than rest, or slightly oversized compared to the rest, or has the bullet seated out just a tiny bit farther than the rest, or one that hits the chamber when the barrel/chamber temp is hotter than it was for the previous rounds, that one pops a primer while the others don't.
And once again, we are back to the condition of the ammunition, and not necessarily the chamber. As you can get popped primers in a 5.56 chamber too, when there are "additional factors" applied.

I totally agree with you that using 5.56 ammo in 223 chambers will lead to higher pressures. From the data available, and expert testimony by Patrick Sweeney, the main pressure event under normal conditions is not dramatic due to a mismatch.

So what I am very interested in is in finding out where in the firing cycle that popping a primer happens. If it was in the first pressure peak I would expect a flattened primer as the bolt is still locked, or if a burst primer I would expect case head expansion measurable by a micrometer. If it happens during a secondary pressure spike and the bolt is unlocked, I would expect the primer to get blown out without any case head expansion, even if the secondary pressure spike doesn't go above SAAMI or CIP pressure maxes.

And that is why having access to data would help me understand where the bullet is when the primer is popped. That is something that the experts haven't told us, or possibly even looked at.

Now I want to build an AR with a gas system that I can turn off with a SAAMI minspec chamber, and run some 5.56 loads through it with that gas turned on and off to see if I can duplicate popped primers with the gas on, and not with the gas off.

And lastly,

Quote:
Yes I can. If the pressure increase puts the peak pressure right at, or very near the limit for popped primers, then the pressure variations from one shot to the next that are evident in any pressure curve data could easily result in popped primers some shots (or maybe even only once out of a number of shots) but not every shot.
Is a statement directly invalidated by you quoting Sweeney who noted that the increases were not dramatic, and NONE of the actuall numbers of pressure increase (claims of 70 to 77k) are responsible for out crimped in primers, although the only data we have access to shows a much less dramatic increase (from the SAAMI spec to the CIP spec when using 5.56 in a 223 chamber).

That data that shows only a modest increase in the primary pressure spike indicates that it is a secondary pressure concern, or possibly a delayed ignition issue that we didn't see in the data we have available.

But, to agree again, yes using 5.56 in a 223 chamber will show a pressure increase. But I can't answer the questions, understanding the mechanisms of failure, without access to actual data, not just "conclusions" which is why I'm talking data and not "conclusion."

Jimro
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Old February 14, 2014, 12:46 PM   #50
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Neither one of you are going to convince the other so how about addressing my last post

Quote:
Pull out any of your manuals that have both 223 Rem bolt data and AR 5.56 data . Now compare apples to apple . Meaning check out the loads that use the same bullets and powders . What do you see as far as max loads for each of those chambering .

What I see in both my Hornady and Sierra books is the 223 is loaded to at least the same max powder charges and many times the 223 will allow a heavier charge then the 5.56 . This is something I have just noticed as of late because I started loading for both 223 Remington for a CZ and 5.56 for my AR .

It seems odd to me that you can put equal charges in a 223 and often can put a heavier charge in the 233 Rem then the 5.56 . Am I missing something here ? More powder means more pressure , Yes?

So back to my first point . Are we talking about factory ammo that is loaded to a different spec then what are books are giving us ?
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