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

[LR1955]

https://www.65grendel.com/forum/showthre...ght=Kaboom

https://www.65grendel.com/forum/showthre...ight=Lapua

Plus this thread for Lapua brass kaboom #3
(Not sure if I missed more)

Failures tend to have near miss sign trend before. Note the countless threads about ring formation that seem heavy Lapua representation (almost all of them either Lapua or Starline). Ring formation right there in the kaboom section.

LE:

I think you understand statistics. Are you positive the populations of brass are identical, the loads identical, the firearms identical, the types and conditions of the shooting among all of the types of brass are identical? Only then can you say that Lapua brass is weaker than others. You know this, I am sure.

Right now you have anecdotal evidence only.

There is a reason Lapua has garnered a reputation among competitive shooters over the decades. It is considered the best quality brass being made today.

LR-55

[lazyengineer]

LE:

I think you understand statistics. Are you positive the populations of brass are identical, the loads identical, the firearms identical, the types and conditions of the shooting among all of the types of brass are identical? Only then can you say that Lapua brass is weaker than others. You know this, I am sure.

Right now you have anecdotal evidence only.

There is a reason Lapua has garnered a reputation among competitive shooters over the decades. It is considered the best quality brass being made today.

LR-55

I understand safety at the field level, and the engineer is responsible for the system safety he develops or endorses.
I see trend specific to one component, and compelling explanation, combined with a large body of near-miss warning signs .

When you see a failure mode trend, and then see a difference that readily explains that failure mode - you call it out.

What I am also seeing, is what I see at the field level safety - of experts who have always said it is one thing, are the slowest to see the obvious when pointed out, and counter to their own bias.

Go look at those 4 photos, look at the fact that 3 kabooms in the last year - only with that brass, amd look at the warning tell of the ring shoulders. I'd fire an engineer who didn't call this out. It might also only fail in certain barrel at certain gas settings. Are you OK with that? I'm not.

[grayfox]

ok. I see 2 circumferential separations, clean-circumferential... one with powder could be over-loaded with a 120-gr bullet loaded tight or in the lands (AR comp has more variation in powder loads than most powders I use, and I use AR comp in the grr and 27.7 in one of my lots... is over), and 1 circumferential case separation in a wildcat with fatigued brass (20-25x loads) admittedly in unknown pressure/load arena for his charge...
Still don't see a generalizing pattern. Unless we point to 3 loads that were at least suspect or over-charged... or something like that.

This one by OP is, well, not circumferential. Looks pretty axially aligned to me. And not in the same spot.

The 2 examples you cite, don't point to any problem with the Lapua's bottom "right-angle" corner either. The failures are up away from that area. So guess I don't see a generalization there on Lapua construction down at that corner...

[grayfox]

The other thing I might generalize from these 3 examples is, bad or poor load practices by the shooters.

Hate to quote John Wayne here, but you can't fix stupid. A nicer way to say it (from my own background), nothing is sailor-proof.

[Klem]

Why stop at the brass manufacturer, why not slam the calibre? They all happened in a Grendel - Grendels are inherently dangerous.

The likelihood Lapua is the cause rather than the symptom is remote.

[DeNinny]

grayfox (and Klem) I understand all of what you say. Clearly there is not enough statistical data regarding this failure to be outright proven, but note that there is not enough data to prove the otherwise or any other failure as well. All of us can only speculate and give our subjective opinions here (which to me is the point...and fun!). It goes both ways with point and counterpoint on a technical debate. As an engineer I am just working with the "data", albeit anecdotal, that's just available in the moment. And of course we should have other failure models on the table here and keep them open too.

And just to be clear on my position/current opinion, I definitely think OP was running a hot load. He was above Hornady's max load with a Hornady bullet. His casing could have easily been Hornady or Norma and still fail.

Also I agree about Lapua being too expensive to be worth it.

[BluntForceTrauma]

My thoughts:

1. Bill Alexander (in conjunction with Lapua) designed the 6.5 Grendel case with the thinner web area to increase powder capacity, knowing that the hardness of Lapua brass could handle it assuming shooters were loading to 50,000 psi average pressure and 52,000 psi average maximum pressure. (Lapua also suggested a shorter neck than used in the 6mmPPC and "6.5"-PPC, which A) also increased powder capacity, B) improved reliability in full-auto, and C) reduced the defect wastage rate in mass production.

2. This all assumes that the feed cones of barrels are matched to this case design. As Bill mentioned in his post I reposted on Page 2, Post #36, of this thread: “Feed cone on the rear of the barrel was changed to support the web correctly…. If you use the cone set up from a 5.56 it does not support the web correctly.” Feed cones for 5.56 in M16s are set up to help the smaller-diameter .223 Remington case find its way into a smaller-diameter chamber mouth. Since the 6.5 Grendel case is fatter and the bullet tip has much more leeway to find the larger-diameter chamber, the same feed cone geometry is unnecessary.

My position takes a little bit from everybody's input and the truth lies somewhere in the middle. Got no problem using Lapua brass as long as my barrel's feed cone area is properly set up to support that web area. Also, I would have no problem using Lapua brass in an "unsupported" chamber, as long as my loads are not above max book. I suppose the converse of my position is: If I don't know my barrel properly supports the 65G case web area, I'd use Hornady brass with its thicker web and accept the reduced capacity. Safe reloading practices are a given.

[DeNinny]

BluntForceTrauma forgive my ignorance, but how does one know the type of feed cone they have for their barrel? How does one know if their barrel has a cone that goes deeper into the chamber than another barrel's cone?

To me, this area, while the round is in battery, is clearly where the case is unsupported. And theory says that the bigger this exposed area, the higher the chance of it promoting a failure under high pressure. All other things equal.

[Zeneffect]

Alternative 3... very far fetched and completely fictitious

Latest batches of lapua are fakes/knock off. At $1 a case and being oh so close to 7.62x39 a Chinese factory has figured out how to make a blue box for profit.

Enjoy the chuckle.

[LRRPF52]

Thank you. No extrusion evidence of gross overpressure. Solid primer strike with a deep impact, which you can only get in an AR15 with a fully rotated bolt. Brass blowout and peel back right at the seem between the web and the body. That brass failed because that brass wasn't supported by a steel chamber wall there. Meaning the chamber cut was too short (too much bevel), the brass head wasn't thick enough to cover that spot with strong enough solid brass head at that depth, or the bolt started unlocking and moving exposing that spot of the brass while still under pressure. Or a tolance stack of all 3 of those combine juuust enough, to kaboom. The correlation this seems to occur only with certain brands, is an item of note.

Section one of your lot of casings and another brand like Hornady, and take a hard look at the head, web, and transition between the two. And any different in how easy each was to cut.

You do you - I've seen this enough times now that when I pick up Lapua Grendel brass - I either scrap it, or run it as a mild fire/forget field load

Please place any Lapua brass you don’t want on the EE.

I’ve been loading Lapua brass in Grendel since 2009. It’s the best brass there is for the cartridge in my experience.

For someone to get a case failure on first firing with a load well-within limits indicates a problem somewhere else.

I’m suspecting the feeding cone not supporting the case. Brass is inherently soft, so it will push around even with low pressures. When unsupported, it will yield like this.

stonehog, was your extractor still intact?

[Zeneffect]

12" barrel, decent charge of a slower burning powder.

Anyone run this setup over quickload to see what pressure is at the port? I bet it's pretty damn high (regardless of software accuracy.) Early unlock and blowout maybe? Maybe you can gain more dwell with a pigtail tube and let pressure drop a bit more.

[LRRPF52]

Both of you are making assumptions.

Ninny,

You are assuming the quality and percentage of brass alloy is the same across manufacturers. Cartridge brass varies in quality and mix (Copper/Zinc). Here's an article from Accurateshooter.com that includes spectroscopy findings. Bottom line, thinner brass can be stronger.

Lazy,

Now, you are assuming both manufacturers cartridges went off in battery, and Lapua failed because it is inherently weaker. None of us know it was in or out of battery. Lapua's weakness, if any, is not common knowledge in the shooting community - quite the opposite. Shooters would quickly figure it out if there were more catastrophic Lapua failures such as this.

Yup. Lapua metallurgy is superior to Hornady’s. People have posted images of sectioned .270 Winchester brass, .338 LM, SAUM, WSM, 5.56, etc. where the thicker cases were assumed to be the higher pressure-tolerant samples, but the opposite was true due to metallurgy.

Companies with lesser strength brass alloy compensate for that with more mass at the web a lot of the time, which can also reduce the case volume.

Concluding that Lapua brass is only worthy of scrap is really one of the most misinformed things I think I’ve seen in a while.

In 6.5 Grendel, Lapua brass is the last to lose primer pocket tightness, for example. I have yet to see a case that will get more loads than Lapua.

This isn’t just true with 6.5 Grendel, but with many other popular cartridges. Here’s an example of a study on .223 brass where the sample sizes were biased against Lapua by a factor of 2-5:

[lazyengineer]

My thoughts:

1. Bill Alexander (in conjunction with Lapua) designed the 6.5 Grendel case with the thinner web area to increase powder capacity, knowing that the hardness of Lapua brass could handle it assuming shooters were loading to 50,000 psi average pressure and 52,000 psi average maximum pressure. (Lapua also suggested a shorter neck than used in the 6mmPPC and "6.5"-PPC, which A) also increased powder capacity, B) improved reliability in full-auto, and C) reduced the defect wastage rate in mass production.

2. This all assumes that the feed cones of barrels are matched to this case design. As Bill mentioned in his post I reposted on Page 2, Post #36, of this thread: “Feed cone on the rear of the barrel was changed to support the web correctly…. If you use the cone set up from a 5.56 it does not support the web correctly.” Feed cones for 5.56 in M16s are set up to help the smaller-diameter .223 Remington case find its way into a smaller-diameter chamber mouth. Since the 6.5 Grendel case is fatter and the bullet tip has much more leeway to find the larger-diameter chamber, the same feed cone geometry is unnecessary.

My position takes a little bit from everybody's input and the truth lies somewhere in the middle. Got no problem using Lapua brass as long as my barrel's feed cone area is properly set up to support that web area. Also, I would have no problem using Lapua brass in an "unsupported" chamber, as long as my loads are not above max book. I suppose the converse of my position is: If I don't know my barrel properly supports the 65G case web area, I'd use Hornady brass with its thicker web and accept the reduced capacity. Safe reloading practices are a given.

I'd say that's a balanced answer. Obviously Lapua has served the more expert members here with proper chambers and gas settings very well, and will continue to do so. For general shooters with potential from a broad spectrum of barrels and such, there is potential for tolerance stacking to become our 4th 2021/2022 Lapua Kaboom, to a degree a general shooter new to this game should be aware of. Safety is everybody's business.

[LRRPF52]

grayfox (and Klem) I understand all of what you say. Clearly there is not enough statistical data regarding this failure to be outright proven, but note that there is not enough data to prove the otherwise or any other failure as well. All of us can only speculate and give our subjective opinions here (which to me is the point...and fun!). It goes both ways with point and counterpoint on a technical debate. As an engineer I am just working with the "data", albeit anecdotal, that's just available in the moment. And of course we should have other failure models on the table here and keep them open too.

And just to be clear on my position/current opinion, I definitely think OP was running a hot load. He was above Hornady's max load with a Hornady bullet. His casing could have easily been Hornady or Norma and still fail.

Also I agree about Lapua being too expensive to be worth it.

The stated load in the OP is not hot, given a normal chamber and the dimensions he has since posted that his chamber will allow.

Hornady’s load data bundles the 120gr GMX with the 120gr ELD-M and 123gr ELD-M, with the 120gr GMX being the limiting bullet with totally different start pressure considerations.

120gr GMX is a solid monolith, whereas 120gr and 123gr ELD-Ms are cup and core, much easier to force into the rifling.

Even if you loaded an additional grain of powder under a harder jacket bullet...as with Alexander Arms published 123gr Scenar data (30.7gr of AA2520 on top of the longer Scenar), you would not see this type of case head failure in a SAAMI spec chamber, and would still be within or at the MAP.

We noticed this about the Hornady data years ago, where GMXs are lumped-in within cup and core bullets. When we reached out to Hornady about the matter, it came down to the additional page count that it would add to their comprehensive cartridge load data books, which are already Biblical in size. They wouldn’t just have to include GMX data for 6.5 Grendel, but every other bore diameter/cartridge that has GMX bullets available for them.

If you are looking for a sanity-check in this regard, or are like me-very skeptical until I see sound evidence, look no further than Hornady’s data for 129gr SP, Interbond, and SST.

You will notice that since there isn’t a GMX in that weight class, the maximum loads for 129gr cup and core bullets are actually higher than their 120-123gr class.

In a properly-cut chamber, you typically have to exceed the brass yield strength to see case head separations or failures on initial firing.

[LRRPF52]

12" barrel, decent charge of a slower burning powder.

Anyone run this setup over quickload to see what pressure is at the port? I bet it's pretty damn high (regardless of software accuracy.) Early unlock and blowout maybe? Maybe you can gain more dwell with a pigtail tube and let pressure drop a bit more.

QL is useless in this respect, for reasons we have covered before. QL can misrepresent an actual 49,000psi load as 64,000psi. The 49,000psi data will have come from a pressure test breech, whereas QL came from someone generating a software model, never having touched an instrumented breech for that specific case.

[LRRPF52]

Alternative 3... very far fetched and completely fictitious

Latest batches of lapua are fakes/knock off. At $1 a case and being oh so close to 7.62x39 a Chinese factory has figured out how to make a blue box for profit.

Enjoy the chuckle.

The Chinese couldn’t even copy the box correctly.

[lazyengineer]

Yup. Lapua metallurgy is superior to Hornady’s. People have posted images of sectioned .270 Winchester brass, .338 LM, SAUM, WSM, 5.56, etc. where the thicker cases were assumed to be the higher pressure-tolerant samples, but the opposite was true due to metallurgy.

Companies with lesser strength brass alloy compensate for that with more mass at the web a lot of the time, which can also reduce the case volume.

Concluding that Lapua brass is only worthy of scrap is really one of the most misinformed things I think I’ve seen in a while.

In 6.5 Grendel, Lapua brass is the last to lose primer pocket tightness, for example. I have yet to see a case that will get more loads than Lapua.

This isn’t just true with 6.5 Grendel, but with many other popular cartridges. Here’s an example of a study on .223 brass where the sample sizes were biased against Lapua by a factor of 2-5:

Overconfident statents on the perfection of that brand has seen 3 kabooms now in 12 months. Please stop overstating its safety to a general shooter with a different barrel. As BFT notes, the tolerance stacking has kaboomed. 3 times now in 12 months. People read and value expert opinion such as from yourself. Catastrophic failures we are not seeing posts about regarding other brass brands.

The good news is unlike 300BO kabooms in 5.56, which are barrel obstructions that hit 80,000+ PSI and Grenade, the Lapua kabooms are due to being unsupported, and so normal pressure and no more than 52,000 psi when they rupture and vent past the unsuported thin Lapua web and shallow seem area. Resulting in relatively minor property damage, at least

[LRRPF52]

My thoughts:

1. Bill Alexander (in conjunction with Lapua) designed the 6.5 Grendel case with the thinner web area to increase powder capacity, knowing that the hardness of Lapua brass could handle it assuming shooters were loading to 50,000 psi average pressure and 52,000 psi average maximum pressure. (Lapua also suggested a shorter neck than used in the 6mmPPC and "6.5"-PPC, which A) also increased powder capacity, B) improved reliability in full-auto, and C) reduced the defect wastage rate in mass production.

2. This all assumes that the feed cones of barrels are matched to this case design. As Bill mentioned in his post I reposted on Page 2, Post #36, of this thread: “Feed cone on the rear of the barrel was changed to support the web correctly…. If you use the cone set up from a 5.56 it does not support the web correctly.” Feed cones for 5.56 in M16s are set up to help the smaller-diameter .223 Remington case find its way into a smaller-diameter chamber mouth. Since the 6.5 Grendel case is fatter and the bullet tip has much more leeway to find the larger-diameter chamber, the same feed cone geometry is unnecessary.

My position takes a little bit from everybody's input and the truth lies somewhere in the middle. Got no problem using Lapua brass as long as my barrel's feed cone area is properly set up to support that web area. Also, I would have no problem using Lapua brass in an "unsupported" chamber, as long as my loads are not above max book. I suppose the converse of my position is: If I don't know my barrel properly supports the 65G case web area, I'd use Hornady brass with its thicker web and accept the reduced capacity. Safe reloading practices are a given.

We have to be very careful of the “somewhere in the middle” positions though, because reality could exist outside of any of the proposed hypotheses.

If the chamber isn’t supported, the barrel needs to be replaced. Over time, an unsupported feed cone area will build a failure node into all the brass fired through it even if they don’t fail like this one did on initial firing.

The problem becomes exacerbated if the brass is sized excessively, work-hardening and misshaping that web area.

This is a common reloading mistake that new and old hand-loaders are prone to making if they aren’t watching headspace and case web management from load-to-load.

The biggest indicator that it has happened is bulging/belting or case head separation.

Another possibility is a chamber cut that isn’t square to the bore, along with lack of support.

It will bias the alignment of the cartridge so that one side of the case body will be fine, whereas the other will bulge out:

[Zeneffect]

Even with a peak pressure swing of +-10k you will still see where the port is in the curve. Since you know the relative pressure that is supposed to be present when bolt opens, and you know the general pressure curve as expected you can extrapolate the theoretical pressure with given pressure variable and simply look to see "yea that ain't right"

It is not useless, one just needs to understand how to use it appropriately foe theoretical purposes.

[LRRPF52]

Overconfident statents on the perfection of that brand has seen 3 kabooms now in 12 months. Please stop overstating its safety to a general shooter with a different barrel. As BFT notes, the tolerance stacking has kaboomed. 3 times now in 12 months. People read and value expert opinion such as from yourself.

The good news is unlike 300BO kabooms in 5.56, which are barrel obstructions that hit 80,000+ PSI and Grenade, the Lapua kabooms are normal pressure and no more than 52,000 psi when they rupture and vent past the unsuported thin Lapua web and shallow seem area. Resulting in relatively minor property damage, at least

I’m not a fan of the mislabel “expert”. The moment someone stops learning and proclaims expert status, the more I am suspicious of their statements.

General shooters have been shooting Lapua brass since the introduction of 6.5 Grendel, because that’s the only brass that existed at the time.

We can’t and shouldn’t rule out the likelihood of chambers that are not cut correctly, especially in the post-2020 era of mass retirement of competent engineers, the cultural acceptance of laziness and excuse tolerance, compacted with supply chain issues.

Sourcing reamers has been very difficult across the industry in many cartridges, which promotes allowances in drops in Toal Quality Management.

There are also many companies who make assumptions about how to cut a chamber and the feeding cone, without having conducted fleet rifle pyramid testing.

They know they can throw barrels out the door due to demand.

There simply isn’t enough pressure being generated to cause this type of failure in a SAAMI spec chamber with proper cartridge support, assuming the cartridge was in battery.

Since Lapua brass is very prominent in the market, it is very presumptive to look there as the failure node.

In every one of the instances you’re referencing over the past year, what barrels were involved? What type of feed cone did they have?