I had a partial case head separation using a 1.8oz buffer

[lazyengineer]

Significant in your case - insignificant in the wider community.

Can you please accept that one possibility is that you are responsible for your own kabooms, so we can move on.

I... uh. my mistake.
I never claimed to have such a kaboom; but from the postings that keep being made, I'm kind of concerned about some different things right now.

Never mind - you have an excellent night sir.

[DeNinny]

I hear you. I was more using your comment as a base for mine - there's a lot of mental masturbation in this thread. Lack of a spec for the feed cones is really more of a SAAMI issue - I don't blame Bill Alexander for keeping his proprietary to maximize revenue from his efforts.

What would be useful is if the OP was able to get a picture of a sized case in the Odin chamber and in the chamber of one of his other barrels. I know that's extremely difficult, but it would be very telling.

LOL there is irony in that we are analyzing a blown load as we mentally masturbate.

Although I would like to see the same thing, it might be very difficult to see the depth of the feed cone from it because there will be a part of it deep into the chamber and there might still be unsupported wall there that cannot be seen.

I actually want to see pics with an empty chamber. And each picture taken from the exact same perspective, and distance. That way we can compare them from the same perspective. Their differences will be truly relative to one another. Maybe we would see feed cone and overall chamber differences. Or not.

[DeNinny]

So I'm a Starline and Hornady brass user, and if I found three kaboom threads on a reloading forum with either of them as a commonality, I would definitely take more caution with my own brass and my practices with said brass because of it. I would check it for the same exact failure signs as shared throughout this thread. Look closely for that belt or line. If there's anything I'm learning from this thread, is that the belt/line phenomena is simply another indication of high pressure.

[DeNinny]

More photos. I was only able to find the slightest ridge forming on 2 cases. #9, and #36. #41 was the kaboom.
[ATTACH=CONFIG]19140[/ATTACH]
[ATTACH=CONFIG]19141[/ATTACH]

These two pics explain/validate a lot. I keep studying them and seeing "stuff".

The line on the first two look to be at the same location, this supports the fact that the rounds were in battery. This also indicates the beginning of the feed cone.

This line is also clearly the weak point, as this is supported by the fact that the failed round is literally torn right there (or very close). The failure looks much like how when you fold a piece of paper to make a crease, then you can more easily tear the paper along that crease. And it is a known fact in metallurgy that when you permanently bend a metal, it becomes weakest right at the bend point. This clearly lines up with what Bill Alexander was saying about how feed cone depth is an issue with some barrels.

The base looks to be failed the most where the extractor was. This makes sense too because as the unsupported brass literally inflated like a balloon, it would have uneven pressure at the extractor as compared to the lugs. This is still speculative, but that's my premise and assumption unless more information is shed to light. Also, because the brass inflated (or flowed) more at the extractor, it also was under stress there, more than at the lugs. As such, that's where the blowout occurred! It initially blew out there, and then a tear line formed along the line, where the metal is the weakest.

Ok so with all this my failure model is becoming clearer and clearer. Great pics!

[grayfox]

So..... 0130 and the dog's "bad dream" woke me up too...
So I just did a quick google on brass case failure and grendel brass failure.
Less than 5 minutes came up with 4 shooters with multiple cases of kabooms among them, both Grendel and AR15. Hornadys, x39 conversions, and some-sorta (223) Walmart brand, and Fiocchi.
I show 2 of the websites here.
Brass failure (65grendel.com)
Catastrophic AR Failure | John1911.com Gun Blog

Dates: 2011.
And 2016.

My earlier point is evidenced here. That is, WE DO NOT KNOW the actual extent and numbers of failures, only those that get reported. In these cases, Lapua is absent. [I would infer from the threads/discussions that the commenters have seen even more of these, but that is an inference and I can't quantify it.] Now in my industry, every failure, even apparent or "looks-like" failures, "almost failures", are logged, analyzed, and reported to a common industry database so others can look/see/benefit, even comment on them.

Face it, this forum is an anecdotal one, relying completely upon reports from whoever posts. "unreported" means "unknown" but is not "un-occurred," so to speak. Now I've found at least 4 other mfrs of brass cases, and could infer a few others, again from the commenters.

In MY industry, we know HOW MANY cases of a given failure are happening, who made them, all the details. In this industry of my persuasion, we can infer or even calculate failure rates, across all the companies, all components, material makes, uses, etc, and not just for our own individual plant.

Lze, this is not the case for our Grendels. Agreed, 3 is worrisome, but now the "universe" of kaboom has just expanded and Lapua brass is not alone, rather one of a small company - a band of kaboomed brothers. Generalize on your own if you want, but it won't fly as any sort of real data-driven conclusion. We do not know how many because not every one gets reported.

All of the instances I found in my 5-minute search were cases with improperly sized ammo, over loaded or warm/over spec ammo, excessive case headspace, headspace, headspace. Occurrences from varying sources, and admittedly across 2 rifle styles, but they are all kabooms. None of these are Lapua. [Again note that I'm not a fan of Lapua nor against it, I don't have a dog in that fight and frankly don't care.]

Common thread, if there be one, and this is inductive of only the ones I could find in a short search, not an exhaustive cataloging of all cases that actually occurred, is not Lapua brass, but - wait for it - excessive headspace. Hot loads a contributing factor. In one of the cases a short barreled rifle was present, a 10.5" which would be similar but not equal to the 12" in OP's case.

Perhaps others can unearth more cases but I've at least shown that one cannot generalize from the voluntarily-reported cases currently under discussion.

Also admitted is that it's (again) late at night/early in the AM, so maybe my rusty brain ain't perkin' like it should. But hopefully somebody sees my point. Somebody more than just my doggie, who is still awake and lying at my feet. Doggie nightmares are a bummer.

[DeNinny]

So..... 0130 and the dog's "bad dream" woke me up too...
So I just did a quick google on brass case failure and grendel brass failure.
Less than 5 minutes came up with 4 shooters with multiple cases of kabooms among them, both Grendel and AR15. Hornadys, x39 conversions, and some-sorta (223) Walmart brand, and Fiocchi.
I show 2 of the websites here.
Brass failure (65grendel.com)
Catastrophic AR Failure | John1911.com Gun Blog

Dates: 2011.
And 2016.

My earlier point is evidenced here. That is, WE DO NOT KNOW the actual extent and numbers of failures, only those that get reported. In these cases, Lapua is absent. [I would infer from the threads/discussions that the commenters have seen even more of these, but that is an inference and I can't quantify it.] Now in my industry, every failure, even apparent or "looks-like" failures, "almost failures", are logged, analyzed, and reported to a common industry database so others can look/see/benefit, even comment on them.

Face it, this forum is an anecdotal one, relying completely upon reports from whoever posts. "unreported" means "unknown" but is not "un-occurred," so to speak. Now I've found at least 4 other mfrs of brass cases, and could infer a few others, again from the commenters.

In MY industry, we know HOW MANY cases of a given failure are happening, who made them, all the details. In this industry of my persuasion, we can infer or even calculate failure rates, across all the companies, all components, material makes, uses, etc, and not just for our own individual plant.

Lze, this is not the case for our Grendels. Agreed, 3 is worrisome, but now the "universe" of kaboom has just expanded and Lapua brass is not alone, rather one of a small company - a band of kaboomed brothers. Generalize on your own if you want, but it won't fly as any sort of real data-driven conclusion. We do not know how many because not every one gets reported.

All of the instances I found in my 5-minute search were cases with improperly sized ammo, over loaded or warm/over spec ammo, excessive case headspace, headspace, headspace. Occurrences from varying sources, and admittedly across 2 rifle styles, but they are all kabooms. None of these are Lapua. [Again note that I'm not a fan of Lapua nor against it, I don't have a dog in that fight and frankly don't care.]

Common thread, if there be one, and this is inductive of only the ones I could find in a short search, not an exhaustive cataloging of all cases that actually occurred, is not Lapua brass, but - wait for it - excessive headspace. Hot loads a contributing factor. In one of the cases a short barreled rifle was present, a 10.5" which would be similar but not equal to the 12" in OP's case.

Perhaps others can unearth more cases but I've at least shown that one cannot generalize from the voluntarily-reported cases currently under discussion.

Also admitted is that it's (again) late at night/early in the AM, so maybe my rusty brain ain't perkin' like it should. But hopefully somebody sees my point. Somebody more than just my doggie, who is still awake and lying at my feet. Doggie nightmares are a bummer.

grayfox I completely see your point. The bottom line is that we will never outright prove that it is any one manufacturer's brass at fault. The only way to prove this is to conduct the exact same failures under the same exact conditions with only the brass manufacturer being different. And let the better brass win. And no reloader or manufacturer in their right mind will want to conduct this experiment. So it is futile to argue it, but you also cannot take it off the table.

Also I will say that after skimming those threads is that there's a lot of assumptions and unsupported statements that the failures were from headspace, but I can't say I agree with the claims of it. Just my $0.02.

[JASmith]

Extremely unlikely - bullets jammed in the lands raise the pressure/velocity, but nowhere near blowing out the base of a case. Some bench-rest shooters deliberately load their rounds long so they jam into the lands as the bolt is closed.

Check your QuickLoad manual and you will see that the bullet in contact with the lands raises the pressure by 5,,00 or 6,000 psi compared to the same load with a jump.

Couple that with an already warm load and one can get truly uncomfortable pressures.

Regarding shooters’ practice of loading the bullet long, that practice generally also includes working up the load with the bullet in the lands. That allows the shooter to find a load with slightly less powder and get acceptable pressures.

[JASmith]

Another cause of unexpected high pressures is failure to trim the cases.

When the case mouth contacts the start of the freebore, there is no space for the neck to expand and release the bullet.

One can see much more, even double, the pressure increase we get with no jump when the mouth is pinned.

[DeNinny]

Another cause of unexpected high pressures is failure to trim the cases.

When the case mouth contacts the start of the freebore, there is no space for the neck to expand and release the bullet.

One can see much more, even double, the pressure increase we get with no jump when the mouth is pinned.

When this specific issue happens, can you see evidence of it at the mouth of the spent casing?

[Fess]

When the case mouth contacts the start of the freebore, there is no space for the neck to expand and release the bullet.

One can see much more, even double, the pressure increase we get with no jump when the mouth is pinned.

I wonder if the Grendel is unusually sensitive to this issue. WAY back when the issue of Quickload predicting overly high pressure for the Grendel was first raised, a plausible explanation was that on this cartridge, the base of the bullet is so close to the primer that the ignition of the primer started the bullet moving. This resulted in a larger effective case capacity before much of the powder had started to burn. If the bullet is pinched in place by the neck hitting the beginning of the freebore, the pressure increase would be even greater (combination of smaller case capacity and higher bullet clamping pressure).

[DeNinny]

I wonder if the Grendel is unusually sensitive to this issue. WAY back when the issue of Quickload predicting overly high pressure for the Grendel was first raised, a plausible explanation was that on this cartridge, the base of the bullet is so close to the primer that the ignition of the primer started the bullet moving. This resulted in a larger effective case capacity before much of the powder had started to burn. If the bullet is pinched in place by the neck hitting the beginning of the freebore, the pressure increase would be even greater (combination of smaller case capacity and higher bullet clamping pressure).

I could see how this is plausible as compared to a more cylindrical case like 223/556. It's all about the diameter of the mouth relative to the diameter of the case. If they are closer in size to each other, then the pressure will relieve itself better and more easily. All the gas in the chamber will head straight out the mouth, relatively speaking. But in the case of the grendel, all the gas in the case now has to funnel through the smaller mouth relative to the case diameter. It's like when you put your thumb on a garden hose mouth. You restrict the mouth area and you create back pressure which lets you spray water at higher velocity. Without your thumb, the back pressure is lower and the water just dribbles out.

[pashiner]

case neck dimensions are critically important. I learned this 2 years ago by blowing up a 300 blackout. I had worked up a good subsonic load with a cast lead bullet, and started forming brass from .223 range pickups. My load (7.2 gn Lil Gun) was just hot enough to cycle the action smoothly (pistol length gas, 16" barrel, std buffer and spring) but a case with a slightly thick neck snuck it's way into my magazine. It chambered, fired, extracted and ejected ok...but tore the lugs out of my barrel extension. left me a cute little 300blk belted magnum case in the brass catcher as a souvenir.

"if it seats, it yeets" is bad advice...even with those little pipsqueak loads!

[stonehog]

Another cause of unexpected high pressures is failure to trim the cases.

When the case mouth contacts the start of the freebore, there is no space for the neck to expand and release the bullet.

One can see much more, even double, the pressure increase we get with no jump when the mouth is pinned.

This is an interesting point. I just went back and checked the case length on all the rounds in my impacted box. the 3 that were showing signs of case stretch all came in over 1.520 max case length! The other cases were all under 1.5175. This may be an additional point in the stacking conversation...

When I prep new brass, I tend to take samples on the first X items - usually 10 or more, and then just do random samples after that. Looks like I can add another "new case prep" item on the checklist to make sure all cases are within spec for length. Honestly - it seems like most brass these days is coming in around .010 under max case length. I also don't know if these cases "grew" on firing to there extended length, but this is easy to measure on the other 150 loaded rounds.

[stonehog]

Here are 3 of the case lengths on cases showing bumps. The last one is the blown case and is the worst of the batch.

[ATTACH=CONFIG]19147[/ATTACH]
[ATTACH=CONFIG]19148[/ATTACH]
[ATTACH=CONFIG]19149[/ATTACH]

[DeNinny]

Here are 3 of the case lengths on cases showing bumps. The last one is the blown case and is the worst of the batch.

[ATTACH=CONFIG]19147[/ATTACH]
[ATTACH=CONFIG]19148[/ATTACH]
[ATTACH=CONFIG]19149[/ATTACH]

These all may have been fine before they failed and deformed. Their added length may just be from the failure...the deformation beyond normal deformation.

On each case, can you please measure that belt depth at the head? Basically from the failure line down to the top of the base. And keep the calipers and measurement visible?

[grayfox]

Definitely should check every case to confirm it is within OAL spec.
Sampling is not acceptable for this step.
What I do, to make it easier, is set my digital calipers to max, 1.520 in this case. Then lock it down with the setscrew. Now every case walks thru those jaws... if it passes, slips easily thru, ok. If not, and I mean if it does not easily slip thru, then off to the side for trim-down. No exceptions!
Maybe it's tight, or even just "stick" a tad at one spot... no exceptions - off to the trim bunch.
Then trim and chamfer inside and out. VLD for the inner chamfer. (This - do for all cases, whether trimmed or not).

OCD types will trim every case every time. If you use a crimp... then need to trim to equal length every case, every time.

ps, what are the OAL's of some of the ones that shot ok... for the record I mean.
And... can you get the shoulder datum for these, maybe not for the one kaboom but the others?

[Klem]

case neck dimensions are critically important. I learned this 2 years ago by blowing up a 300 blackout. I had worked up a good subsonic load with a cast lead bullet, and started forming brass from .223 range pickups. My load (7.2 gn Lil Gun) was just hot enough to cycle the action smoothly (pistol length gas, 16" barrel, std buffer and spring) but a case with a slightly thick neck snuck it's way into my magazine. It chambered, fired, extracted and ejected ok...but tore the lugs out of my barrel extension. left me a cute little 300blk belted magnum case in the brass catcher as a souvenir.

"if it seats, it yeets" is bad advice...even with those little pipsqueak loads!

Pashiner,

Your Blackout situation is interesting, but might not be related to bullet release.

Can I ask, how do you know it was an overly-thick neck that prevented the bullet from being released?

What thickness is your Blackout brass at the neck? For example, unfired Grendel Lapua is 0.0135" at the mouth (relatively thick). Gemtech 300BO brass is 0.01" at the mouth (about as thin as it gets).

A Grendel SAAMI chamber is reamed to .300" inside diameter (ID) at the neck. A typical cartridge will be about 0.290" outside diameter (OD). That allows 0.01" of space around the neck for bullet release - plenty of space. The other issue is not having too much space around the cartridge so it doesn't split on firing.

Not all Grendel chambers will be reamed to exactly 0.300". My Lilja neck is tighter. Spent cases measure 0.2925" OD at the neck. Fired cases will have sprung back slightly so the chamber will be maybe 0.2935". Still, plenty of space for shot release. As long as your loaded cartridge is not the same dimension or wider than your chamber then you are good to go for bullet release.

In this table due to slight differences in bullet diameters you get slightly different amounts of space around the neck when in battery; note the column 'OD Loaded'. With all the subtle variation from manufacturers there is still plenty of space for all bullets to be released.
[ATTACH=CONFIG]19150[/ATTACH]

FYI, 6.5Creedmore has a slightly tighter chamber mouth than Grendel at 0.2960". SAAMI specifies no more than 0.295" OD for loaded Creedmore ammo. That is 0.001" space for safe shot release - or in other words, 0.0005" between the cartridge and the chamber wall.

I have a tighter-than-SAAMI 6.5x47 match barrel with a 0.286" mouth. It requires all cases to be neck-turned so loaded ammo is no more than 0.2842" OD. I cannot use factory ammo in that barrel without kaboom. After all that, it is no more accurate than my other normal barrels.

Stone,
You can get an idea of the mouth dimension of your Odin chamber by measuring the OD of spent cases. Then measure the OD of those loaded unfired rounds in the photo. Check the difference for shot release and eliminate that as a reason for kaboom.
Note: Be careful of dings on the mouth from the spent cases hitting the receiver on the way out. the cases need to be perfectly round to get a good measurement.

[LRRPF52]

More photos. I was only able to find the slightest ridge forming on 2 cases. #9, and #36. #41 was the kaboom.

[ATTACH=CONFIG]19138[/ATTACH]
[ATTACH=CONFIG]19136[/ATTACH]
[ATTACH=CONFIG]19139[/ATTACH]
[ATTACH=CONFIG]19140[/ATTACH]
[ATTACH=CONFIG]19141[/ATTACH]
[ATTACH=CONFIG]19137[/ATTACH]
[ATTACH=CONFIG]19142[/ATTACH]

Do you have a headspace comparator gauge (Stoney Point or Hornady)?

I’m interested in what your fired headspace is from those previous cartridges. If you can measure without including the primer, which would require a universal decapping pin so you don’t re-size the brass in the same operation.

That would be helpful to know what your fired headspace is.



This one looks like there is a line I’m not used to seeing, right above the case web:

[LRRPF52]

This is pointless.

Kaboom 1 - Lapua in an AR15 with an Odin BBL by one user

Kaboom 2 - Lapua in a bolt action rifle by another user

Kaboom 3 - Lapua in an AR15 with a PSA BBL by yet another user


All other brass: No Kaboom.
Lapua represents a small portion of reloading brass in use; and has an engineering aspect different from all others, at the location of Kaboom's

Conclusion - Lapua can't be a component of that?

Reported catastrophic failures on a forum that doesn’t even scratch the surface of all actual users out there. That’s the statistical assumption fallacy.

Most 6.5 Grendel owners out there are not even aware of this forum, or do not have memberships. There are thousands of people who view the forum without membership, and don’t see a lot of the images.

I have friends personally who have had all kinds of problems, broken extractors left and right, order new ones, break them soon after.

We tried to figure out what was going on to no avail.

Me (with untold thousands of rounds fired through RLGS, MLGS, and CLGS Grendels of most/all barrel lengths over the years with large moving boxes full of brass to back this up): “Dude, why are you breaking so many extractors?”

Him: “I don’t know!”

Years go by.

Me: “Hey, PPU just had a huge shipment of ammo come in.”

Him: “I still have hundreds of that older stuff, the ones that were recalled you remember, but I didn’t want to send them back because I figured I couldn’t get anymore.”

Me: :eek:

[LRRPF52]

I wonder if the Grendel is unusually sensitive to this issue. WAY back when the issue of Quickload predicting overly high pressure for the Grendel was first raised, a plausible explanation was that on this cartridge, the base of the bullet is so close to the primer that the ignition of the primer started the bullet moving. This resulted in a larger effective case capacity before much of the powder had started to burn. If the bullet is pinched in place by the neck hitting the beginning of the freebore, the pressure increase would be even greater (combination of smaller case capacity and higher bullet clamping pressure).

Fun fact: I have never had Lapua brass reach the 1.530” case length from stretching that I’m aware of.

I have had older PPU brass exceed that length even from a single firing.

Generally, chambers are cut with additional neck length, but you really have to watch for it with softer brass in lower pressures, and any brass run at higher pressures.

My .260 Rem brass needs trimming, otherwise I can’t load it.

A lot of .308 Winchester once-fired I have needs trimming.

My Lapua and Hornady Grendel brass....I have never trimmed. The most case length I get to is typically 1.5260” or a bit less.