Which is the better indicator of impending head separation?

Cut one and see. Better to sacrifice one than a batch or your safety

Chop one in half and take a look.

The 'bright ring' is the reason to check. The check is to determine.

That being said, tossing a case or two to ease one's fears is an economical solution.

Usually, not invariably, the bright ring of incipient head separation is quite low on the case, just above the web.

If they have only been loaded 1-3 times and you're getting that ring you may well be over pressure. Or you could have resized the cases wrong. Most of the time when I see cases separate from improper sizing or over use it happens very near the rim. With the shiny ring where it is located it appears to be due to over pressure to me.

The max pressure recommended for 243 is 60,000 PSI. The pressure signs that people try to use to determine over pressure loads don't even show up until you're over 70,000 PSI. If you're still within 1/2 gr of where you started getting pressure signs you are under 70,000 psi, but could very well still be over 60,000.

Without expensive equipment it is impossible to know the exact pressure you're getting. But using a chronograph is the next best thing. If the load manuals say that 42 gr is a max load with the bullet/powder combo you've chosen and it should be leaving the muzzle at 3100 fps, then 3100 fps is your max load. Not 42 gr of powder. You start low and work up to 3100 fps and stop at or below that speed. Most of the times the numbers in the load manual will closely match what you get in the real world. But I've seen certain rifle/bullet/powder combo's that would reach the max speed listed with as much as 2 gr less powder than listed as max.

This is the primary reason I like to have a chronograph. If you want to load anywhere near max loads I think it is a good idea. Without one you're working blind and have no idea if you're getting close to being over loaded. It's like driving a car with no speedometer, only a warning light that comes on when you reach 90 mph. By then you're already well over the limit.

If you find that they are bad I would love to get one for training, as I have never felt a bad one and I'd use it to learn.

barnfrog said:

A few of the cases have a ring round them slightly more than half way from the head to the shoulder. . . When I run a bent paper clip along the inside of the case wall it feels absolutely smooth.

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That ring appears to be the result of a chip caught under a reamer flute while cutting either your chamber or your die. The paperclip test, if you understand how it works, is definitive.

Cut one if you want, but I wouldn't suggest it's necessary.

The ring is also where some case trimmers stop ,if using a drill mounted cutter which works off of the shoulder.

Something as simple as the plastic ammo box can leave a ring like that on brass. I would find it unusual for a case to separate that high on a case.

I have a Garand with a 'new' barrel; whoever was running the chamber reamer that day must have been a little distracted... my fired brass has chatter marks in the center of the cases. These are actually raised on the brass... you can run your finger over them and feel them, but they have no effect on the brass, or the longevity of it. Originally I was worried that it would lead to case failures in that area... but some of my -06 brass is 30 years old, and I'm just now starting to see stretched cases... at the expected location, down by the case head.

I don’t use my best indicator to check, just a cheap Chinese one, it’s plenty accurate for measuring case wall thickness without harming the case.

This is the fixture I built.



This is a cut away case but you don’t have to do that to measure, it’s just for visual effect.

Quit loading near max and they will last a long time.

Thomasss said:

Quit loading near max and they will last a long time.

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A lot of stretch is caused by simply sizing the case more than necessary for a given chamber.

If one has to trim every time, this is likely the case (no pun intended).

Set the sizer so a sized case fits the chamber like the one at 1:15 in this video.



and the case has no where to go with mild or max loads.

Just cranking the die down to contact, is really an unknown. If that setting sized the case “under”, firing, even with minimum loads, will blow the case back out. Then sizing it under again leaves the excess material on the end of the neck, where it needs to be trimmed off, again. The brass one cuts off during trimming had to come from somewhere and this migration is where separations come from.

You have a tool groove in your chamber.Look in there with a bore scope and you'll see it.I've seen a few chambers that do that.Doesn't hurt a thing.One of my 308's is like that.Kinda handy for keeping each rifle's brass separate.

That ring looks to far up the case to be a case head separation indicator??

I have had one (1) separation in a 5.56. It is not the big deal that some make it out to be. No, you rather not want it to happen but it is not a catastrophic event. Just a pain to get the broke piece out of the barrel. I do not put a paper clip in every case I reload.

Archie said:

The 'bright ring' is the reason to check. The check is to determine.

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This.

barnfrog said:

When I run a bent paper clip along the inside of the case wall it feels absolutely smooth.

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Done, nothing to report.

Your chamber or die has a chip ring. Ignore it.

Also, as @Rule3 said, a head separation is not life changing. If you don't have an appropriate brush and rod, it'll end your range trip, nothing more.

Walkalong said:

It has potential for hot high pressure gases exiting the rear of the action and harming you, and since it can be prevented.

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I think gas venting out the back is a near certainty in the case of a head separation. . . but there's very little chance of it hurting you. In my experience, and I have separated a few cases, it sounds slightly different and smokes a bit. It can certainly be prevented once you learn to look for it.

It's nothing like a head rupture.

Walkalong said:

Yep, but first run a feeler in there for a bit, that way you'll start to learn what stuff you are feeling looks like inside.

Separations can happen there, but it is usually lower above the case head where the brass thins down.

Read some about it here.

https://www.thehighroad.org/index.php?threads/incipient-case-head-separation.734058/

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This would mirror my experience with case head seperation.

edwardware said:

It's nothing like a head rupture.

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Been there, done that. No fun.

barnfrog said:

So I just full-length sized a bunch of Remington .243 cases that have been reloaded once. The powder charge was near max, a couple tenths of a grain below where I had seen pressure signs when I developed the load. A few of the cases have a ring round them slightly more than half way from the head to the shoulder.

View attachment 988650

When I run a bent paper clip along the inside of the case wall it feels absolutely smooth. Should I be erring on the side of extreme caution and tossing these few that have the ring, or trusting my fingers that there is no serious defect?

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Im no expert but those look like the stiff charges have pushed the brass outwards a bit extra evident by the rub marks during primary extraction