Case neck separation?

[XL105]

I bought a bunch of 308 brass on another site. He said they were once fired FGMM brass, fired out of bolt action rifles. Received them yesterday and I’m looking through some of them, I’m finding some with a ridge/rim around the necks of some of them.
they are head stamped FC 308 Win with sealed primers. Some of the primers look flat (not sure if it’s the sealant making them look flat) with some cratering.
If they are once fired brass I wouldn’t thing it’s necks starting to separate.
What’s happening?

 

[MagnumManiac]

That is not separation as far as I can see.
Looks like a ring from the chamber, maybe some swarf was caught in a flute and left a ridge in the chamber.
Separations on necks nearly always occur as a jagged tear where neck meets shoulder due to work hardening.

Cheers.

 

[rijndael]

It's interesting that the line isn't consistent in distance from the mouth.

 

[XTR]

I'm waiting to see what this really is. I've never seen cases look like that before.

 

[D-4297]

It appears that it could be tooling marks from a automatic loading machine , where the cases weren't "straight up " in the rails .

 

[rijndael]

Why would the carbon ring stop at the at this line? Is it a line noting a thickness variation/step?

 

[Webster]

I bought a bunch of 308 brass on another site. He said they were once fired FGMM brass, fired out of bolt action rifles. Received them yesterday and I’m looking through some of them, I’m finding some with a ridge/rim around the necks of some of them.
they are head stamped FC 308 Win with sealed primers. Some of the primers look flat (not sure if it’s the sealant making them look flat) with some cratering.
If they are once fired brass I wouldn’t thing it’s necks starting to separate.
What’s happening?

On one of my Rem 700 rifles I can pretty much count how many times a case has been fired by the extractor making a ding mark on the rim. I don't see it on your cases. Like someone else said neck cracks run the length of the neck not around it. Never heard of neck seperation. I would steel wool the necks and see if the ring disapears. Fire a couple and see how it goes. Is there any depth to the ring mark? Is it just the oxide rubbed off? If the primers are sealed I would think they were fired once. If any civilian reloaded them they wouldn't put sealant on them. They are marked 308 not 7.62 MM. That would indicate to me they were never military brass, if so why were they sealed. Civilian use carteidges are not sealed. I am not sure but I think Mil carridges have sealant on the bullet also? Is there any on the neck I.D.?

 

[Uncle Ed]

The cases might be from MK 316 MOD 0 and fired from a multitude of 7.62 military rifles.
If the primers are still crimped that would be my guess.
Load and shoot them, the marks are not the start of a neck separation.

Cartridge, caliber 7.62mm special ball, long range, MK 316 MOD 0 (United States): A 175-grain round specifically designed for long-range sniping consisting of Sierra MatchKing hollow-point boat-tail projectiles, Federal Cartridge Company match cartridge cases and Gold Medal match primers. The propellant has been verified as IMR 4064 (per NSN 1305-01-567-6944 and Federal Cartridge Company Contract/Order Number N0016408DJN28 and has a charge weight per the specs of 41.7-grain

 

[338 dude]

I’ve never seen any cases quite like that either to me it seems like a chamber problem but different lengths up and down the neck is what really doesn’t make any sense

 

[chutem]

On one of my Rem 700 rifles I can pretty much count how many times a case has been fired by the extractor making a ding mark on the rim. I don't see it on your cases. Like someone else said neck cracks run the length of the neck not around it. Never heard of neck seperation. I would steel wool the necks and see if the ring disapears. Fire a couple and see how it goes. Is there any depth to the ring mark? Is it just the oxide rubbed off? If the primers are sealed I would think they were fired once. If any civilian reloaded them they wouldn't put sealant on them. They are marked 308 not 7.62 MM. That would indicate to me they were never military brass, if so why were they sealed. Civilian use carteidges are not sealed. I am not sure but I think Mil carridges have sealant on the bullet also? Is there any on the neck I.D.?

I have a bunch of once fired Federal Gold Metal Match brass with sealed primers. Not military.

 

[XL105]

The carbon ring seems to follow the ridge that formed around the the neck, but not all have the carbon ring with the ridge and not all brass has this ridge. You can feel the ridge with your fingernail.
If I’m not mistaken all FGMM brass has a sealant applied to the primers at the factory. So it appears that these are once fired brass.
Still baffled by the inconsistency to where the ridge is formed on the neck.

 

[K22]

I've seen more problems at the range with other shooters using cases from unknown sources than any other reloading issue. I spend 2 to 3 day a week at the range.

I know, a lot of guys do it, hell, I did it myself years ago and with today's component shortages I understand the draw. I stopped doing it years ago but that's just me.

My best advice - if you are new to reloading start with new cases whenever possible. If you insist on using cases from unknown sources inspect each case thoroughly, know how to size them, test them in your rifle chamber before loading, and monitor them carefully after each firing.

Ok - you can now blast me with rebuttals.

 

[JFrank]

Excellent advice from K22

 

[Thud]

Solution - don't buy once fired brass from an unknown source....

 

[XL105]

I've seen more problems at the range with other shooters using cases from unknown sources than any other reloading issue. I spend 2 to 3 day a week at the range.

I know, a lot of guys do it, hell, I did it myself years ago and with today's component shortages I understand the draw. I stopped doing it years ago but that's just me.

My best advice - if you are new to reloading start with new cases whenever possible. If you insist on using cases from unknown sources inspect each case thoroughly, know how to size them, test them in your rifle chamber before loading, and monitor them carefully after each firing.

Ok - you can now blast me with rebuttals.

Excellent advice from K22

I can appreciate you’re opinion on buying used brass. Of course inspection is necessary, that’s what I’m currently doing. But when I plan on loading large quantities on a none precision rifle, I tend to lean on being lil more frugal. But for my precision reloading I but new brass and prep accordingly.
The problem I have with it is it doesn’t help answer my question. What is the cause of this.

 

[JFrank]

"It appears" just from my distant perspective that some one has seated bullets with a neck bushing that was about .005 under a loaded round.

 

[Dusty Stevens]

They were fired in an m1a

 

[K22]

I can appreciate you’re opinion on buying used brass. Of course inspection is necessary, that’s what I’m currently doing. But when I plan on loading large quantities on a none precision rifle, I tend to lean on being lil more frugal. But for my precision reloading I but new brass and prep accordingly.
The problem I have with it is it doesn’t help answer my question. What is the cause of this.

Understand your motivation - not being critical of it. I like frugal - but I like to avoid problems better especially when they negate frugally.

I don't know if I can help answer your question because of the uncertain history of these cases but I'll try. Assuming that there are no fatigue cracks or signs of incipient head separations you can attempt the following:

You can rule out cosmetic issues by cleaning an polishing the necks with with 0000 steel wool then carefully inspecting under magnification.

You can rule out dimensional issues by full length sizing the carefully checking in your rifle chamber without forcing the case into chamber. I broke a Rem extractor years ago doing this so be careful.

Hope this is helpful

 

[bozo699]

I've seen more problems at the range with other shooters using cases from unknown sources than any other reloading issue. I spend 2 to 3 day a week at the range.

I know, a lot of guys do it, hell, I did it myself years ago and with today's component shortages I understand the draw. I stopped doing it years ago but that's just me.

My best advice - if you are new to reloading start with new cases whenever possible. If you insist on using cases from unknown sources inspect each case thoroughly, know how to size them, test them in your rifle chamber before loading, and monitor them carefully after each firing.

Ok - you can now blast me with rebuttals.

No rebuttal here!.... sound advice!
Wayne

 

[divingin]

You can rule out dimensional issues by full length sizing the carefully checking in your rifle chamber without forcing the case into chamber. I broke a Rem extractor years ago doing this so be careful.

If you do get a case stuck in the chamber and are unable to get it out by working the bolt, I've had luck with opening the bolt handle as far as it will go without undue force, then continuing the bolt travel while firmly tapping on the case base with a cleaning rod inserted from the muzzle.

I had a batch of "once-fired, reconditioned" LC 308 cases that would chamber fine, but stubbornly stick after the first firing. Turns out they missed part of the sizing during "reconditioning". FL sizing took care of that problem, but had to tap out quite a few cases before I ID'd what was causing it.