Case head seperation

[lrgrendel]

Had these two catastrophic failures last week. Never had a failure like this before.
One blew the magazine out the bottom. It severely got my attention.

29.1 gr AA 2520. Tula primer. 123 AMAX. LAPUA CASE.
30.9 gr CFE. CCI 450 primer. 123 SMK. LAPUA CASE.

7 to 8 firings on the cases and I have got some split necks recently.
I have over 2000 rounds fired through this Upper.

I have sent the Upper back to the manufacturer to get it "checked out" as I am very hesitant to fire it now but I do believe it is the brass.

My question is, how or when do you judge to stop reloading certain cases to prevent a repeat of this situation?

[Joseph5]

My guess is, and this is just a guess, you have excessive headspace and your cases are stretching to fill the chamber, then sized down, shot and excessively stretched, repeat, blow out. You would need to measure the case length on an unfired round then case length after shooting to know how far your case is stretching. Another possibility is your chamber was cut for a bolt with a face depth of 0.125 and your bolt has a face depth of 0.136 which seems more likely than a chamber cut to deep and using the correct bolt. The Grendel Spec is for a bolt face of 0.136 deep. When people started using bolts made for 7.62x39 they were only cut 0.125 deep so they chamber had to adjusted accordingly. This is were the Type I and Type II bolts come from that you may have heard mentioned. Someone more knowledgeable than me will be along soon to chime in but I think I am on the right path to diagnose the problem. Unless they were bad brass a lot of people have gotten 15 - 20 or more reloads with Lapua brass.

[wfa17332]

I can't tell you exactly "why" this happened to you, but it's important to visually inspect each fired case before reloading. Specifically, look for a bright ring on the body of the case just forward of the case head. If such a ring exists then you should make/use a "tool" created (for example!) from a "paperclip" (You can still buy them, can't you?); take the paperclip, bend it "back and forth" (that was how most paperclips were actually used back "in the olden days"!) until it breaks. You will have a very sharp point. Using the longer of the two pieces make a small "hook" (90 degree bend), and insert it into the case. If the case is about to separate you will feel a "catch" as the point slides up/down the wall. Such a case should go into the "brass scrap" container.

[NugginFutz]

Case head separation, as you may know, usually occurs as a result of repeated firings and sizings. The case expands when fired, and is subsequently squeezed back into shape, when sized. When being sized, the brass has to go somewhere, and that somewhere is up, toward the neck. As the case is repeatedly sized, enough brass defects/migrates to the neck that the webbing near the case head becomes dangerously thin.

How soon that thinning occurs generally depends on two factors. 1) Head space and 2) Pressure levels.

Below are two segmented .308 cases.

On the left is a 2x fired case shown for comparison, while on the right, a 7x fired Lapua. Note the thinning of the case wall, just above the webbing.



The case on the right was measured at the point in question, and showed a .010" thinning at that point. It was also exhibiting what I refer to as the "Shiny Belt of Impending Doom", which led me to check the case for thinning. I did this with an RCBS case tool, but a simple piece of bent wire with a sharp edge (resembles a dental tool) will suffice.

The above case could have likely gone on for another loading or two without separation. Or not. I chose to take that entire box of cases out of service, simply because of stories like yours.

Split necks are also symptomatic of brass that has been sized too often. Because brass is a metal that Hardens when Worked, it becomes more and more brittle with each successive resizing. I personally consider split necks to be a not-so-early of end of life warning.

If I were in your shoes, I'd keep an eye on your brass after each firing, and watch for signs of thinning (bright ring, detectable thin wall). You can also check and make certain you are not overworking your brass when sizing. If the sizing die is set too deep, you can create an excess head space condition, which will drastically impact case life.

Hope this helps

[GarandThumb]

As mentioned, you can make a took out of a paper clip. I do this periodically with all my cases. Usually my primer pockets loosen up before but i have culled a few based on what I found with the paper clip tool:

https://www.youtube.com/watch?v=UUDClnQcsMQ&list=PLAH4yl5r83rsGVWBPOg3-E_7-gC7o7LF_&index=1

[LR1955]

Had these two catastrophic failures last week. Never had a failure like this before.
One blew the magazine out the bottom. It severely got my attention.

29.1 gr AA 2520. Tula primer. 123 AMAX. LAPUA CASE.
30.9 gr CFE. CCI 450 primer. 123 SMK. LAPUA CASE.

7 to 8 firings on the cases and I have got some split necks recently.
I have over 2000 rounds fired through this Upper.

I have sent the Upper back to the manufacturer to get it "checked out" as I am very hesitant to fire it now but I do believe it is the brass.

My question is, how or when do you judge to stop reloading certain cases to prevent a repeat of this situation?

LRG:

It isn't headspace. You have enough experience to know that and if you only got a headspace separation, it wouldn't have blown the magazine out of the well or blown the floor plate off the magazine.

You had an out of battery firing and as a result, separated the head.

This can be caused by a primer that wasn't seated deeply enough but most likely is due to part or parts on the bolt or bolt carrier that are worn out, causing the firing pin to hit the primer before the bolt goes into battery.

Look at the firing pin, the hole in your bolt face for the firing pin, then worn parts on the bolt and bolt carrier.

It is extremely difficult to determine exactly what happened with an out of battery firing so sometimes you just have to replace parts.

Lapua brass goes fifteen plus loadings in the Grendel.

Headspace separations in gas guns won't blow magazines out the bottom of the rifle. Out of battery firings will. I know because I have had out of battery firings and even one with a Grendel.

LR55

[NugginFutz]

...

Headspace separations in gas guns won't blow magazines out the bottom of the rifle. Out of battery firings will. I know because I have had out of battery firings and even one with a Grendel.

LR55

LR55 - short of blowing out magazines, what other symptoms are present in instances of case head separation? I've never experienced either a case head separation or OOB firing with a rifle of any type. I've only had one case where a 9mm SW M&P had a case head separate, but now I am not certain if it was not a smaller scale OOB firing.

Thanks, btw, for staying on top of these issues. Feedback such as yours is what keeps me coming back.

[lrgrendel]

Ok. A quick update.

Did some work tonight with a buddy. ( Thanks Dave! )

Measured a lot of fired AND sized cases with a HORNADY shoulder gauge. They were very consistent.
Fired came out at 1188.
Sized came out at 1185/1185.5

(No head space issue)

BTW I use a Forrester full length sizing die.

I have fired 2340 shots using 300 pieces of LAPUA brass. As mentioned I have discarded almost 50 pieces due to splitting in the neck. ( I found 3 tonight )
About 90% of all firings were in or around maximum pressures.

Now we cut the 3 split cases plus one I was suspicious of and the evidence speaks for itself.
I marked the one we found with a really thin wall near the case head with 2 black marks.

Now, up to now I was convinced it was the brass, till LR1955 wrote what he wrote!!

The Upper was put together by a very reputable company and they will receive it tomorrow. With only 2340 shots put through the upper, I will be very disappointed if there is any wear that would have caused this issue.

I have read and taken a mental note of all the responses to my post, thanks.
For now ALL this brass has been put to one side and I await a response from the Upper manufacturer.

I will post an update when I find out anything.

[LR1955]

LR55 - short of blowing out magazines, what other symptoms are present in instances of case head separation? I've never experienced either a case head separation or OOB firing with a rifle of any type. I've only had one case where a 9mm SW M&P had a case head separate, but now I am not certain if it was not a smaller scale OOB firing.

Thanks, btw, for staying on top of these issues. Feedback such as yours is what keeps me coming back.

NF:

Normally a headspace separation happens during a normal firing process. The pressure is contained in the chamber as under any firing condition. Head separates, is extracted, and ejected. Body of brass remains in chamber. Sometimes it falls out but most of the time you need to remove it with a bore brush or a stuck case extractor. I noticed mine because I saw something way too small eject and of course the next round won't chamber at all. They won't blow a magazine out of the mag well because the firing was normal.

He had an out of battery firing and as a result, the head separated. Most of his cartridge was chambered when it went off so a huge amount of pressure was released into the receiver. Since the bolt and bolt carrier were probably mostly closed with his rifle, the gas was channeled downwards into the magazine, blowing it out the bottom of his magazine well. Mine blew some ammo out the bottom of the magazine. Bolt lugs were sheared, brass split, bolt carrier damaged. Took hours to get the mess cleared. Luckily, no damage to receiver. Got a new bolt carrier and bolt and no problems. No one knows why it happened, either. Only that it did happen.

LR55

[lrgrendel]

LR1955

"Lapua brass goes fifteen plus loadings in the Grendel."

Besides the obvious "loose primer pockets" and "split necks", are there any other signs you might see to make you not load a particular case again??

[LR1955]

LR1955

"Lapua brass goes fifteen plus loadings in the Grendel."

Besides the obvious "loose primer pockets" and "split necks", are there any other signs you might see to make you not load a particular case again??

LRG:

I believe those two are the big ones.

I have thrown out brass that I knew was loaded too hot when I shot them. When I shot these particular loads, the noise of the shot was somewhat hollow and the recoil not quite right. Inspected some of the brass to see flat primers and brass flow into the ejector. I stopped shooting it and threw it away.

I am surprised that your Lapua brass is not lasting longer. I will shoot mine ten times, trim it and shoot it another ten times. I figure that is enough so throw it away.

I have only split necks when using a Lee sizing die. Their sizing die is too tight at the neck so you end up work hardening the necks. I got rid of the Lee dies and had to custom order a set of Grendel dies. Never had a problem after that. I now use Redding dies and never a problem. I also use Dillon spray lube and I believe the lube has a lot to do with brass life.

Of course the chamber in your rifle could be too tight and the brass is getting sized down with the bullet in the neck. That can also cause cracked necks. Too much pressure created. Could also cause blown primers and out of battery firings.

Maybe you ought to ensure the chamber in your Grendel is not too small?

LR55

[lrgrendel]

LR1955
"Maybe you ought to ensure the chamber in your Grendel is not too small?"

It arrived back to the manufacturer today. I will ask them to inspect the BCG and check the chamber.
I have had a few issues where I had wanted to eject an unfired cartridge and it got stuck in the chamber and was very difficult to get out. A few times but not many.

[pds]

LR1955
I have had a few issues where I had wanted to eject an unfired cartridge and it got stuck in the chamber and was very difficult to get out. A few times but not many.

Stuck cases could be the result of the bullets being jammed into the throat and or lands. This could result in the case not being fully chambered and the bolt not fully closed and hence the locking lugs not fully locked. If bolt and firing pin are not correct this would allow the rifle to ignite a round when the trigger is pulled without the bolt being fully locked. You may have an incorrect bolt and or firing pin. Just a thought.

PDS

[LR1955]

LR1955
"Maybe you ought to ensure the chamber in your Grendel is not too small?"

It arrived back to the manufacturer today. I will ask them to inspect the BCG and check the chamber.
I have had a few issues where I had wanted to eject an unfired cartridge and it got stuck in the chamber and was very difficult to get out. A few times but not many.

In that case, and if the cartridge was a handload and not a factory load, you weren't bumping the shoulder enough. Factory loads should chamber and extract with ease.

Before we got fixated with all the OAL gadgets, we sized the cases down until they would chamber and extract easily. It was simple and always worked.

If you aren't bumping the brass enough, you are forcing the bolt carrier and bolt to work a lot harder to go into battery. That is a bad thing. It will also cause problems with pressures and blown primers. That too is a bad thing. It may go into battery enough to shoot but not enough to function well. Thus causing headspace separation.

Bump the shoulders back so the brass chambers and extracts easily. Then keep seating the bullet deeper until a case with the bullet seated will chamber and extract easily. Then see if it fits the magazine. If it doesn't, and you want to shoot from the magazine, seat the bullets deeper until the cartridge fits the magazine.