LRRPF52 Wrote:When seasoned, older reloaders who put high load counts on brass say, “This one gets up to 50 reloads and others don’t even approach that.”, that’s a pretty huge indicator of the quality of one brass over others.

Early-on with 6.5 Grendel, we had guys on the forum who got 20 or more loads with Lapua brass, shot the headstamps out. No other brass that I’m aware of has achieved that many loads.

When I have shot and reloaded Federal 6.5 Grendel brass, for example, I lost primer pockets within 2 loads when shooting through the AR-15.

Interestingly, this did not happen when shooting and loading it through the Howa Mini bolt-action rifle. Even with me loading well over 1-2 grains higher than book loads in the AR-15, the primer pockets stayed nice and tight in the Howa with Federal brass.

Hornady brass has been the next-best performer for me in terms of longevity, number of reloads.

Other seasoned reloaders here on the forum have reported as many as 8-12 loads. Depending on what dies, pressures, gas system lengths, and chambers are used, you might see that brass become unusable at 5 loads.

This catastrophic failure happened with new Lapua brass on his first firing of that batch, #41 of 50 hand-loaded cartridges.

That brings me to the question, can we see the heads of the 40 other fired pieces of brass if we haven’t seen them already?

StoneHendge Wrote:It's got nothing to do with the spec. The manufacturer likely effed up making the barrel. We've seen it here countless times on here barrel issues which were likely due to reaming too shallow or too deep. Easy enough to do with whatever tool they do the feed cone with too.

lazyengineer Wrote:It never creeped out - and there is no speculation- it's staring us in the face, and the heavily quoted Alexander confirms that a chamber dimension needs to be just so with that brass. Walls don't hold pressure, they are a gasket. Case heads hold pressure. No case head where there is no chamber wall = not holding pressure.

LRRPF52 Wrote:6.5 Grendel isn’t a relatively high pressure round for modern cartridges. It has a much lower Maximum Average Pressure than 5.56x45, .308 Winchester, and other rifle cartridges that have been developed over the last 30 years. Most of your factory ammunition is running in the 47,000-49,500psi range, with MPSMs that can’t exceed 52,000psi. These pressures were more common from the late 1800s-1950s, for reference.

LRRPF52 Wrote:Excessive headspace can be caused by a combination of shoulder location and incorrect (too deep) bolt face depth. The brass grows to fill the void, since cartridge brass is so soft (Alloy 260 ~70/30 Copper/Zinc). Brass is just a high pressure gasket designed to hold the primer, propellant, and projectile together for repeating firearms for easy storage, transport, and stacking in feed devices. The chamber pressure immediately swells it into the shape of the chamber and bolt, from which it rebounds some back between its original shape and the obturated shape. Different brass manufacturers have their proprietary processes that create stronger brass, or easier to mass-produce brass. Lapua brass is known around the world for decades to have the strongest construction, last for the most reloads, and have the smallest SDs in weight, volume, neck thickness, flash hole geometry, etc.

LRRPF52 Wrote:So during many excess headspace scenarios, the vast majority of the pressure is contained well within the chamber, but as the brass finishes its rearward growth, it stretches past the point of full chamber support, and there is enough residual pressure to blow out the now-exposed portion of brass.

LRRPF52 Wrote:Since the extractor is still intact, that steers us towards excess headspace and not an over-pressure event. When you have case failures in the AR-15, it’s very common to have extractors destroyed. (A sidebar anecdote on this is that Hk placed a pin inside the barrel extension in the extractor clock location to help prevent this from happening on the Hk416.)

LRRPF52 Wrote:I don’t think we can say that Lapua brass definitely played a role in this. The only possibility there would be this particular piece of brass, not Lapua as a whole, and even that’s a stretch.

LRRPF52 Wrote:Lapua 6.5 Grendel brass fleet experience at this time is in the millions of samples in production-who knows how many times those have been reloaded. Bill’s initial work was one of the only smaller companies that actually did pyramid testing on his rifles not just for reliability, but for accuracy and durability. In addition to that, he did high sand/dust testing regularly, flying out to a large training center in New Mexico where the surface is covered in sharp rocks, sand, and dust. If any of you recall the Future Weapons episode on 6.5 Grendel with “Mack”, it was filmed there. That was all done with Lapua brass loaded cartridge by Alexander Arms. 6.5 Grendel wasn’t some small project with minimal testing, but an unusually-extensive and professionally-executed developmental program for a non-big-named company at the time.

So Lapua brass isn’t a new, unproven, or anecdotal report-based “it works for me” component in this equation. It was already well-established in the 2000s due to extensive design, testing, and proven performance in large production. That has only grown exponentially since then. Janne Pohjoispaa of Lapua, who was instrumental in the development of .338 Lapua Magnum and 6.5x47 Lapua (superior design compared to 6.5Creedmoor), was the lead engineer in developing the finer details of 6.5 Grendel brass, working in conjunction with Bill Alexander. These are not only formally school-trained engineers specific to firearms and ammunition, but both had many years of experience prior to this developing cartridges for military and industry requirements. Bill worked on the UK’s answer to the NATO PDW requirement with a cartridge called the .224 Boz, was trained within UK MoD how to do depot-level inspection and maintenance overhauls on AR-15s in UK service (by Eugene Stoner and other senior engineers), did .50 Beowulf, 5.45x39 in the AR-15 (.221 Genghis), and then 6.5 Grendel.
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Many of the reference rifles used in velocity testing, in conjunction with pressure test breeches, were Alexander Arms AR-15s. For example, Hornady’s sample rifles include 14.5” and 18” AA AR-15 carbines. I have personally confirmed this with Hornady’s engineers, who went and looked in their armory to verify those test rifles for the 8th, 9th, and subsequent editions of their load manuals.

LRRPF52 Wrote:I already addressed the hypothesis of too much propellant earlier. 29.x grains of AA2520 under a 123gr cup and core bullet is not the max load with a chamber with his measurements.

Hornady’s published loads for AA2520 are limited by the Monolithic 120gr GMX, which is longer than some of the 140gr cup and core bullets. That limits case capacity due to intrusion, and also resists being driven into the lands more than cup and core bullets. His stated load is well under max, which is likely why we didn’t see the extractor blow out, primer intact, case head looking ok other than the failure in the side of the brass.

LRRPF52 Wrote:Everything really points to excessive headspace. No other variable is needed or indicated from what I’m seeing here, not having the components in my hands.

Klem Wrote:Lazy,

The only thing 'staring us in the face', are the pieces of a catastrophic failure, and even in that there is a lot of information missing. For example, how the round was assembled by the OP at the time and its actual specs. Yes, that Lapua case failed, but that does not prove it is the cause. It could be a host of other reasons that have nothing to do with the brass manufacturer. And until you can rule out all other possible causes you cannot say with confidence it was Lapua's fault.

The only other potential cause you can confidently rule out is Hornady, and every other gun manufacturer, every other powder and powder manufacturer, etc. Yes, it was not a Hornady case in the breech at the time. But that does not prove which brass is stronger. It is just one piece of evidence.

That the case was Lapua and implying it was the cause, then generalizing to all Lapua brass beggars belief. Please stop with the Lapua hate, it is hijacking the thread.

LRRPF52 Wrote:When seasoned, older reloaders who put high load counts on brass say, “This one gets up to 50 reloads and others don’t even approach that.”, that’s a pretty huge indicator of the quality of one brass over others.

Early-on with 6.5 Grendel, we had guys on the forum who got 20 or more loads with Lapua brass, shot the headstamps out. No other brass that I’m aware of has achieved that many loads.

When I have shot and reloaded Federal 6.5 Grendel brass, for example, I lost primer pockets within 2 loads when shooting through the AR-15.

Interestingly, this did not happen when shooting and loading it through the Howa Mini bolt-action rifle. Even with me loading well over 1-2 grains higher than book loads in the AR-15, the primer pockets stayed nice and tight in the Howa with Federal brass.

Hornady brass has been the next-best performer for me in terms of longevity, number of reloads.

Other seasoned reloaders here on the forum have reported as many as 8-12 loads. Depending on what dies, pressures, gas system lengths, and chambers are used, you might see that brass become unusable at 5 loads.

This catastrophic failure happened with new Lapua brass on his first firing of that batch, #41 of 50 hand-loaded cartridges.

That brings me to the question, can we see the heads of the 40 other fired pieces of brass if we haven’t seen them already?

LRRPF52 Wrote:We’re just talking ideas here, not picking anyone person apart, so be assured this isn’t personal.

LRRPF52 Wrote:5.56x45 is loaded to higher pressures than 6.5 Grendel. The case geometry for 6.5 Grendel is considerably different than 5.56x45, which required numerous design changes in the bolt, extractor, tighter tolerances held on the barrel extension (due to warping from heat-treating that is fine with 5.56 but not Grendel), magazines, etc. I’ve had pretty extensive discussions with Bill about this offline over the years. The things he covered are aspects of the rifle and cartridge he learned the hard way during development, on top of formal engineer training and experience with his prior work. It’s a fascinating story really.

None of these design nuances are secret, since anyone could order AA Barrel/bolt combos and rifles to inspect if they wanted to back then.

LRRPF52 Wrote:I provided numerical data, namely the fact that millions of 6.5 Grendel Lapua brass and ammunition have been manufactured and fired and reloaded from 2004-present.

LRRPF52 Wrote:It doesn’t matter what the metallurgical details are when we can see the actual performance.

Klem Wrote:Lazy,

Your statistical conclusion is flawed.

I have had no Lapua kabooms...ever. How does that reconcile with your experience?

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

stonehog Wrote:The three I have shown individually were the ones I could see a ridge forming on. The rest look pretty normal albeit a bit rough from the chamber. I don't see this sort of chamber imprint on the other brass I've inspected (FC, Starline, Hornady) so far. My bet is the odin chamber is a bit rougher than the Faxon or PSA. I also looked back at notes showing that I had checked headspace with the Odin BCG and bolt in the Faxon barrel (passed) but I don't see notes that I ever checked the Odin bolt in the Odin barrel. Doh! I probably expected it to be OK as it was a matched barrel and BCG/Bolt purchased. It will be interesting to see if I get similar extraction issues and/or brass markings with the Monster bolt I am replacing it with (that has passed headspace).

BTW - thanks for all the deep dives here folks - I'm learning a ton about both the AR platform as well as the Grendel. Good stuff!

DeNinny Wrote:I understand. I made the point because BluntForceTrauma stated that there is no spec on it. And I'm just saying that *if* it did have a spec, then customers could reject a barrel based on it and also the manufacturer would have more incentive to check and make sure their barrel wasn't effed up before it made it out of the production line. Another way of looking at it is without a spec then there's less quality control over the making of it. And you wouldn't be able to hold a manufacturer accountable if they effed one up.

lazyengineer Wrote:Also, please correctly run the statistics on the odds of 3 Kaboom's of 6.5 Grendel in the last 12 months; with all 3 to exclusively involve only Lapua brass. I look forward to seeing what the odds are of that by your assessment.

Klem Wrote:...Lapua is unsafe in your loads, but not mine? Conclusion:
1. Lapua is unsafe.
2. Your handloading is unsafe.

(Hey, you did ask)

Klem Wrote:Lazy,

I did not say it was Conclusion 2 - I just pointed out the logical conclusions.

You have had three Lapua kabooms in 12 months while I have not had any in 30 years. I did ask you to reconcile the difference given you are blaming the manufacturer and not entertaining it could be you (and 'friends'). If you are not going to reconcile it by stating the obvious then again, please, stop polluting the thread by involving the public in blame-shifting.

lazyengineer Wrote:So... you are saying bad reloaders pick Lapua? I wonder what the statistical odds are of all 3 of the kabooms in the last year are, of only being Lapua?