Near miss probably dodged

[J.d. Popkes]

Happened to catch the one on the right, inspected with wire on some other ones, felt a ridge, looks like I best throw it away.

 

[Straightshooter1]

Yeah, always a good idea to keep a close eye out on the cases as they're being processed.

 

[Rook 6]

Toss the lot. Ain’t worth it.

 

[Coyotefurharvester]

Have you figured out why a potential case separation was occurring in your reloading ?

 

[markm87]

I've been getting a rash of those lately in 6.5cm. I have one die set up for my buddy's 2 guns. I have to size to run in the AR10 LMT gun, but that gives some trouble in the Bergara bolt gun... or vice versa.

We have a can of ammo that can be shot in either gun because my buddy is too ADHD and disorganized to dedicate ammo to specific guns.

Break a case? Toss it in the scrap bucket for money later.

 

[XTR]

You may know this, but for those who don’t. That comes from pushing the shoulder too far back on your brass, and too far back, doesn’t take much over the course of a few reloading’s.

Every time you fire a case, the firing pin drives the case to the front of the chamber, the sides expand grip the chamber, and then the bass expands to meet the bolt face and it stretches in a 308-based case where you see that one or maybe even a little further back, and on 223 it’ll happen a little further forward.

So if you push your shoulder back 4thou each time you resize when you shoot it four times it stretches ~16, though usually it’s bumping back about 10 thou+ that gets you into trouble. Multiple chambers not cut with the same reamer is another commonality.

I’ve had small primer Lapua 308 shot at full up FTR loads for so many reloads I lost count. In 10 yrs of competition (my reamer on all barrels) I think I split one neck, the rest of the brass I threw out to loose primer pockets. Never had a case head separate. Not that I have’t had one, just not with brass sized for the chamber. I bump right at 2thou. To be consistent at that close you need to anneal.

@markm87 measure his fired brass. One of his chambers is longer than the other. Need to sort till he can get two matching chambers.

 

[topclass2017]

I've taken to depriming and wiping my brass clean at the range as something to do while my barrel cools. A benefit is I am able to look at each piece of brass thoroughly, and any that looks at all wonky is separated for further examination once I get home

 

[M-61]

You may know this, but for those who don’t. That comes from pushing the shoulder too far back on your brass, and too far back, doesn’t take much over the course of a few reloading’s.

You are right. I’ve written this scenario many times on this site.
One has to have an exact understanding of what happens when the trigger is pulled.
You’ll see more of this separation as time goes on. Some have included shoulder bumping as one of many steps in reloading.
Therefore we will see more case separation. The only thing I see that you left out in your description is the primer once it ignites the powder gets pushed back to the bolt face. Once the case springs and releases its death grip on the chamber walls it comes back and reseats the primer.
That’s fine but if you would like to what your headspace actually is without going crazy, just take the fired case. Deprime it. Take your fired primer, just start it in the primer pocket, chamber and close the bolt.
Withdraw it. The amount the primer is protruding is your headspace. Keep pushing those shoulders back and I guess you’ll get to the point the primer falls in your hand. Not good.
I like your part with the firing pin strikes primer and FiRST pushing the case forward.
I’m writing about bolt actions and what I do.
Anyway well done.

 

[Webster]

Yeah, always a good idea to keep a close eye out on the cases as they're being processed.

View attachment 1758663 View attachment 1758664

I don't have a good drawing but I believe the .200" line and back to the case head is not in the chamber. More than you would think is outside the chamber so the extractor can grab the extractor groove. My guess is that has something to do with stretching and failure at this location. Maybe someone has a drawing showing how much case is outside the chamber?

Update:

just found this on internet:
In a typical firearm, the amount of the cartridge case that remains outside the chamber—often referred to as the unsupported case area—usually ranges between 0.110" and 0.160". This exposure is necessary to allow for proper functioning of the bolt, extractor, and feeding mechanisms.

 

[TA17rem]

Case separation, one of the reasons I don't pick up other people's brass at the range..

 

[J.d. Popkes]

You may know this, but for those who don’t. That comes from pushing the shoulder too far back on your brass, and too far back, doesn’t take much over the course of a few reloading’s.

Every time you fire a case, the firing pin drives the case to the front of the chamber, the sides expand grip the chamber, and then the bass expands to meet the bolt face and it stretches in a 308-based case where you see that one or maybe even a little further back, and on 223 it’ll happen a little further forward.

So if you push your shoulder back 4thou each time you resize when you shoot it four times it stretches ~16, though usually it’s bumping back about 10 thou+ that gets you into trouble. Multiple chambers not cut with the same reamer is another commonality.

I’ve had small primer Lapua 308 shot at full up FTR loads for so many reloads I lost count. In 10 yrs of competition (my reamer on all barrels) I think I split one neck, the rest of the brass I threw out to loose primer pockets. Never had a case head separate. Not that I have’t had one, just not with brass sized for the chamber. I bump right at 2thou. To be consistent at that close you need to anneal.

@markm87 measure his fired brass. One of his chambers is longer than the other. Need to sort till he can get two matching chambers.

I also anneal every time and bump .002

This has 15 reloads, some kinda hot

I think it was just it’s time

 

[Webster]

I also anneal every time and bump .002

This has 15 reloads, some kinda hot

I think it was just it’s time

Been reloading since 1970. Never had a case separation. At least 20 reloads on my Lapua 6BR brass. Is the problem caused by the person chambering the rifle. I can not believe gunsmiths have go/no go guages for all of the at least 25 popular cartridges.

 

[Coyotefurharvester]

Often I'm not bumping shoulders at all, even after several reloadings.

 

[Webster]

Often I'm not bumping shoulders at all, even after several reloadings.

If you can close the bolt easily they don't need to be bumped.

 

[J.d. Popkes]

Been reloading since 1970. Never had a case separation. At least 20 reloads on my Lapua 6BR brass. Is the problem caused by the person chambering the rifle. I can not believe gunsmiths have go/no go guages for all of the at least 25 popular cartridges.

It’s not the gunsmith, it’s not my sizing.

This brass has been ridden hard, and it went plenty long. I know what you’re saying about br brass.

Just posted it because it’s the first time I’ve had it happen to me personally, I’m fairly certain of the cause, just a simple reminder.

 

[Tommie]

Eventually it will happen (unless some other issue arises first). Well maintained brass in cartridges with minimum body taper and sharp shoulders tends to last longest.

 

[J.d. Popkes]

Toss the lot. Ain’t worth it.

I did. Got some shiny new stuff swapped in. I’m such a cheapskate I don’t know why I want to eke out every bit of my case life. The alternative is so much more expensive and hazardous it’s silly.

 

[J.d. Popkes]

Have you figured out why a potential case separation was occurring in your reloading ?

Just worn out I suppose. Usually my primer pockets go first, I’ve been waiting for these to give up, they been ran like a rental. These are from my last barrel. Like I said, just waiting on primer pockets to loosen up, but this time it’s the case web. Live and learn to keep fighting another day, luckily

 

[TA17rem]

It happens, sometimes human error setting the die or what have you no big deal just grab new brass and move on is what I say. LOL I had it happen with my 22-250 ackley and changing presses no big deal.

 

[K22]

I've posted this many times but perhaps it bears repeating. This is how I avoid case problems for bolt rifles:

1. Start with virgin brass & dedicated to a specific rifle.

2. Rotate the use of the brass so all pieces receive an equal amount of firing and sizing.

3. Measure fire case head space with a bump gauge and adjust F/L die to zero bump. Often this is all that is necessary for the several firings. In my experience, it's the radial dimension that causes most of the chambering difficulty. The F/L die will solve that problem without repeatedly bumping the shoulder if the die is set up for zero bump.

4. Bump the shoulder only when necessary and only the amount necessary to achieve adequate chambering, usually .001 to .002 is all that is necessary for bolt rifles.