Early signs of case head separation

[Martin52]

These pics show early signs of case head separation and are taken inside the case at the .200 line.

There was very little indication on the outside of the cases other than a very fine line that could have been easily missed.

To be safe, I looked inside with my borescope.

One image shows a shiny line/crack developing, the other two show dark lines that circle the interior at the .200 line.

These are 3 x fired 0.308 large rifle primer cases. The load was 43 gr IMR8208 behind a Berger 155.5 projectile (COAL 2.91). Shoulder setback was minimal from first firing, 0.001. BR2 primers.

Posted just for general interest.

 

[piie]

Can you feel it with the paperclip method? Interested wether its detectable at such early stage.

 

[Martin52]

No, not detectable even with the dental pick that I use for this purpose.

 

[hoz53]

No, not detectable even with the dental pick that I use for this purpose.

since they are going to the scrap bucket anyhow id grind the side of at least one of them out so i could get a better view of wats going on.

 

[Martin52]

Yes, I will get around to doing that.

 

[boltfluter]

Martin,

I am assuming these must have stretched quite a bit on the first firing to die at such a young age.

Paul

 

[XTR]

I'd be looking for why this is happening at 3 firings. Something doesn't add up.

In over a decade I've lost one lot of 308 cases to head separation and that was from shooting some WW brass in 2 different rifles chambered with different reamers. I've never seen that not caused by excess shoulder bump, as in my case having 2 chambers with different lengths or the die set too low. I've got cases with somewhere in the range of 12-20 firings on them. Every other case that I've tossed has been due to eventual primer pocket opening up.

Or as noted by boltfluter it was really short on the first firing.

You do make a good point, if you see a line on the outside there is one on the inside too. I've got a lot of once fired 223 that was grossly over sized and if I'm not careful with them they show signs after the first time I use them.

 

[Webster]

View attachment 1329156View attachment 1329157View attachment 1329158

These pics show early signs of case head separation and are taken inside the case at the .200 line.

There was very little indication on the outside of the cases other than a very fine line that could have been easily missed.

To be safe, I looked inside with my borescope.

One image shows a shiny line/crack developing, the other two show dark lines that circle the interior at the .200 line.

These are 3 x fired 0.308 large rifle primer cases. The load was 43 gr IMR8208 behind a Berger 155.5 projectile (COAL 2.91). Shoulder setback was minimal from first firing, 0.001. BR2 primers.

Posted just for general interest.

The real question is why are there signs of separation after 3 firings? Looks more like stains than stretching of the metal. I have over 20 reloads on my 6BR cases. I would shoot them a few more times and photo the interior. Reload and shoot until there are a more definite indications. How are you cleaning the inside of the cases. Could be mineral or soap stains. After tumbling rinse with distilled water to remove possible water or soap residue. You can buy distilled water in stores for steam irons for 99 cents a gallon. Distilled water will at least remove the possibility of stains.

 

[SKWERLZ]

I’ve seen something similar( not in three firings thankfully) but you could always feel it with a pick or paper clip.

 

[Walt Krafft]

OP did not say what rifle he was using. Short case life is a known fact shooting M1A's.

 

[jackieschmidt]

I will echo what most have said, the fact that you have signs of early head separation is an indication something is not right. Analyze the problem.

 

[K22]

Were the cases new cases and only fired in this rifle?

What was the fired case head space measurement? What was the sized case head space measurement?

It's highly unusual for incipient head separation to occur in the 3 reloads especially if the cases were new to begin with and only fired in that rifle. I would definitely have the rife examined by a competent gunsmith. I would also suspend reloading for this rifle until you can identify the cause.

I personally have never experienced this condition and have only seen it twice in over 50 years of shooting. Once was with a break open 243 Win rifle and the other was with a 300 Win Mag, both rifles where not mine but fellow shooters.

In the first case, we determine the rifle had excessive head space. The cases showed a clear line of incipient failure. We sectioned the case to confirm it. Rifle was returned to mfg. and repaired.

In the latter case. the details are a little foggy in my old brain since it was many years ago, but if I recall correctly, the owner was not sizing off the shoulder but the belt. I've never loaded belted magnums before and know very little about them so I may be mistaken but I think that was the issue. Anyway, he experienced complete, through wall case failure. It was really something to see. The fix at the time was he stopped reloading this cartridge and just used Federal Premium Factory ammo which made sense since the rifle was only used for big game hunting trips out west and Canada - it was not a large volume use range rifle. In other words, he only shot a few rounds a year out of it, a few sighters and if he got lucky, a few at game animals.

 

[358WCF]

Just last year I had some new 35 Whelen brass show a distinct bright ring after the 1st firing. A sharpened, bent paper clip agreed there was a problem. I contacted the manuf. & was told to return the whole lot. They replaced it with new & also returned the original (which I'm using the 30 undamaged cases for 338-06 now with great success) with a note saying their brass was at minimum headspace & that the rifle should be checked for excessive headspace. A 30-06 no-go gauge doesn't. Same rifle since '88 & never a problem before or since. It was the new brass.

 

[M-61]

I've never seen that not caused by excess shoulder bump

Yes.
Shoulder 'bump' seems to have become a 'step' in many peoples reloading process.
Shoulder bumping to me (I'm talking Bolt actions) is a remedy to correct a fault.
The bolt is stiff opening for example.
Making 'bumping' a part of your reloading routine is asking for case failure. I try to work the brass as little as possible. Should the bolt have a stiff lift well the push the shoulder back some. It's not a set number.
Your cartridge fires. The brass (with the help of 50,000 psi) fills the chamber. The headspace (which is IN the chamber) is from the closed face of the bolt to a point on the shoulder (called datum line). If you have excessive headspace the brass reaches these two points by stretching. (I'm not mentioning spring back). Now if the charge was hot enough one can imagine lifting the bolt may be a bit stiff. This case has stretched far enough to cause this. By 'bumping' the shoulder back a bit it will now chamber nicely. To constantly 'bump' ( for no reason) this shoulder therefore increasing headspace your brass's life is shortened. The brass will do the stretch thing only so much.
Some cartridges are much easier on brass than others. I have a 222 with maybe 25 reloading's on it. Never a 'bump' needed.

 

[AlNyhus]

Checking the case head-to-datum on new, unfired cases is a must. A good example is a 243 factory barrelled hunting rifle I just finished up.

The factory chambers head space is spot on. New out of the box Lapua 243 cases fit the chamber perfectly with .0015-.002 case head-to-datum clearance. Recently manufactured Winchester brand 243 brass has .014-.016 case head-to-datum clearance.

5 of the Winchester cases were loaded with the bullets jammed hard into the rifling, lightly oiled before the first firing and have been used as foulers. After the first firing the case head-to-datum was perfect. All 5 have been fired 7 times now (scope changes, foulers, etc) and look like they just came out of the bag....both inside and out.

I feel you get one chance for good cases and it's on that first hit.

Good shootin' -Al

 

[M-61]

A bit lost on two things:
Are these loaded factory ammo?
And what did you 'lightly oil'?
I just got lost on that.

 

[Ned Ludd]

Several years ago, a shooting buddy had problems with case-head separation at an F-Class match using hand-loaded .223 Rem ammunition. In talking with him about it, it seems he had been bumping the shoulders of Lapua brass back to the original (box) dimension. In my hands, Lapua .223 Rem brass grows somewhere in the neighborhood of .006" to .008" on the first firing. So he was likely bumping the shoulders back by about that much. His brass that was having case-head separation issues had been fired three times. So it can happen fairly quickly if the shoulder is set back excessively.

Your use of the borescope to examine the suspect cases is a very smart way to visualize what's going on inside the brass in a manner that is more revealing than the old paper clip method. Thanks for sharing.

 

[6MMsteve]

setting headspace tight on a new barrel is a good thing, if you have the means to do it, and new brass to do it with... imho

 

[K22]

Yes.
Shoulder 'bump' seems to have become a 'step' in many peoples reloading process.
Shoulder bumping to me (I'm talking Bolt actions) is a remedy to correct a fault.
The bolt is stiff opening for example.
Making 'bumping' a part of your reloading routine is asking for case failure. I try to work the brass as little as possible. Should the bolt have a stiff lift well the push the shoulder back some. It's not a set number.
Your cartridge fires. The brass (with the help of 50,000 psi) fills the chamber. The headspace (which is IN the chamber) is from the closed face of the bolt to a point on the shoulder (called datum line). If you have excessive headspace the brass reaches these two points by stretching. (I'm not mentioning spring back). Now if the charge was hot enough one can imagine lifting the bolt may be a bit stiff. This case has stretched far enough to cause this. By 'bumping' the shoulder back a bit it will now chamber nicely. To constantly 'bump' ( for no reason) this shoulder therefore increasing headspace your brass's life is shortened. The brass will do the stretch thing only so much.
Some cartridges are much easier on brass than others. I have a 222 with maybe 25 reloading's on it. Never a 'bump' needed.

This is good advice in my opinion. He says it better than I could have. It's not a set number and one should not just blindly set the shoulder back a prescribed amount without regards to the rifle chamber. My remarks pertain only to bolt rifles.

This is why I've always believed that the ultimate gauge is the rifle chamber. The various bump gauges are useful in aiding to set up the die to obtain a measurement of the optimum case head space once determine by the rifle chamber.

In my experience, often, case headspace length is not the issue causing hard chambering but rather growth of the radial dimension. Each rifle is different and one size doesn't fit all but I've often set the FL die of some rifles so the die just touches the shoulder with zero to .001 or less set back. These cases chamber perfectly.

When I neck sized many years ago, I could go several firings without having to full size. The problem was predicting when without having to check each time I loaded a batch of cases. This is why I switched many years ago to full sizing but with a "measured' approach to only size the minimum amount so the cases chamber properly.

 

[SKWERLZ]

Checking the case head-to-datum on new, unfired cases is a must. A good example is a 243 factory barrelled hunting rifle I just finished up.

The factory chambers head space is spot on. New out of the box Lapua 243 cases fit the chamber perfectly with .0015-.002 case head-to-datum clearance. Recently manufactured Winchester brand 243 brass has .014-.016 case head-to-datum clearance.

5 of the Winchester cases were loaded with the bullets jammed hard into the rifling, lightly oiled before the first firing and have been used as foulers. After the first firing the case head-to-datum was perfect. All 5 have been fired 7 times now (scope changes, foulers, etc) and look like they just came out of the bag....both inside and out.

I feel you get one chance for good cases and it's on that first hit.

Good shootin' -Al

I always note my new brass vs the go gauge as well so I know exactly what’s going to happen on the first firing so I don’t have to jam or false shoulder stuff.