7.62x54R Pre-case head separation (pics)

[juniustaylor]

I have reloaded these a few times, didn't write it down to recall for sure but probably about 3 times. Didn't seem to last long. 12 out of the 20 had a noticeable ring around them, some had a light crack forming on half of the case. The two worst ones are in the middle picture. One is severely cracked and the other actually leaked gas through it. It has gas marks around the entire thing, I am lucky it did not separate during extraction or I'd probably still be trying to dig it out or be buying a broken shell extractor.

First picture, there is no correlation between this picture and the middle picture. These are 2 separate cases that I chopped in half. I thought by removing the carbon (on the right) that it would make the ring easier to see, turns out it didn't. You can see the ring well in the charred up one.


Next photo. These were the worst 2 out of the 12 damaged cases.


This is a close-up of the absolute worst. You can really see a nice crack there.


It looks like 8 cases were left and are "okay" looking but they're going into the trash. I may keep these other two around for specimens to look at. Figured I'd share. These are Winchester Metric brass (Sellier & Bellot). I don't recall them being loaded hot, just moderate. I figured they'd last longer than 3 reloads but evidently not. May just be because they're actually S&B brass with Winchester's name on it.

[juniustaylor]

I also considered... I full length size these because I have 2 Mosins (M91/30 and M38). I wonder if one may have a more generous chamber and allows the case to stretch more, then during the sizing process, the brass gets really worked. I still figured the neck or shoulder would have given out before the web.

[lklawson]

I don't reload so this is academic for me (at least right now. maybe in the future...).

If the cases are work hardening would annealing resolve this issue or is the damage already done by the time it's been fired and, at that point, the brass has been spread?

If annealing would solve the issue, would it be worth it to get a torch setup or just cheaper to replace the brass?

Peace favor your sword,
Kirk

[The Only Sarge]

Looks like they are collapsing in on themselves. Head space comes to mind....or really lack thereof.
What kind of run on do you have before engaging the rifling?

[juniustaylor]

I read in my Hornady 7th Ed. reloading manual that you usually don't have this type of problem in rimmed cartridges. In rimless, you can because if the dimension between the shoulder and the case head is a tad short, the case basically has to slam against the bolt face and then the shoulder seals and such and such. Basically that's what I understood and they showed a picture that matches what mine look like with that inner worn ring around the bottom of the case. The manual just said that since rimmed cartridges headspace on the rim, then it's different. My Mosin rifles both are within specs. I had "made" a Go, No-Go gage. I do have a field gage as well. That one passes the bolt won't close on it. Bolt won't close on No-Go thickness and will close on Go thickness. So, the headspace is fine in both of them. Bullets are normally seated around 2.9'ish to 3". They are under the max length and above the minimum. Don't know what kind of space there is between the bullet and the throat of the rifling, never checked. I have loaded several times for other rifles and got more use out of cases than this. I really figured it could have been the Czech brass just wasn't as good.

Kirk, I don't think annealing would do much. Usually when you anneal a case it's up at the shoulder out to the case mouth as that part gets really worked during the reloading and firing processes. You would want the brass relatively softer there than you would down towards the head.

I'm not too worried about it. It's not like I shoot the crap out of my Mosins anyway and I do have a gob of mil-surp corrosive crap if I had to shoot it. I'll just have to acquire more brass or just buy all new ammo and reload it when I eventually shoot it up. Other brass has been pitched.

[The Only Sarge]

Go-No Go is good enough to rule out headspace in my book. Just a thought.....
At the end of the day....could be crappy brass

[juniustaylor]

could be crappy brass

That's about all I've got to work with. I don't know if I've really heard a whole lot of great stuff about S&B Brass. I'll eventually try to score up some Prvi Partizan and try reloading them when I get them shot up. I hear that Prvi brass is pretty decent.

[The Only Sarge]

It is....but S&B brass is "supposed" to be pretty good.....

[juniustaylor]

Alright, I did some reading in my Lyman reloading manual on the topic of case head separations and other brass issues. Lyman said that some reloaders can get lots of reloads out of brass but says that the typical reloader should figure about 8 times (including the original factory load) for rimless cases and then throw the brass out. For belted magnums they suggested 2 to 3 reloads, and then finished up with rimmed as somewhere between rimless and belted.

So, with this sort of guideline, I guess it was about time for these to go, I am sure that I loaded them 4 times and then their original factory load puts them at 5 total loads, so I guess it was their time to go. I then read about the subject of headspace but am sure that is not my issue as I previously stated.

I also read about their opinion on sizing brass. They mentioned that lots of resources state that brass life can be prolonged by neck sizing only. However, they said they recommend full length sizing as it ensures that the cartridges will feed, chamber, and extract when especially needed in hunting situations. They said there is no real advantage to neck sizing only as you won't notice any real gain in case life.

The next topic was on annealing. They absolutely don't recommend it. They said that the temperature must be kept within certain limits and it cannot really be achieved by the average DIY'er. They said that by the time you even thought about annealing the case necks due to work hardening, the brass is already on it way out the door anyway.

Of course, most all of this is paraphrased. I am glad to have some form of guidelines on the life of brass, the bit of info on the headspace, opinion on neck/full-length sizing, and the annealing. If you don't have a Lyman 49th, definitely it's a manual worth looking into. I feel they went in good detail to discuss those certain items. I don't think my Hornady 7th did that good on explaining much. I was glad to see that they recommend full length sizing as the norm. Well, guess that's all.

[The Only Sarge]

Not being critical here....just an observation over the years.
Lyman does their own research. Hornady cuts and paste others.

[juniustaylor]

Not being critical here....just an observation over the years.
Lyman does their own research. Hornady cuts and paste others.

Hahaha, you're more than likely right.

[normsutton]

Jun

load with the slowest burning powder that cartridge calls for ,the cases will last longer , like H 414

NORM

[GeneCC]

A round will temporarily adhere itself to the walls of the chamber. I don't recall the technical term for this. I do know that this adhesion is part of the expansion of the brass and it's a mild form of attachment to the walls of the chamber. Part of the extraction process is to undo this temporary adhesion. The MN has a fine extractor which manages this problem.

The round will expand equally in all directions while firing. The brass will adhere to most of the chamber wall. Where ever the brass can expand it will expand, including the area that lies just forward of the base. Where you're seeing failures.

If you're full length resizing each time and you have too much setback between the base and the face of the bolt the brass forward of the base of round will stretch out with each firing cycle. Eventually between the full length resize and the set back you get an area where the brass thins and then fails.

Annealing is great for necks. The neck is often where cracks will begin. Annealing provides some strain relief from work hardening caused by resizing.

On the bases you want less yield to prevent case rupture. So it's a bad idea to anneal down there.

Please consider neck sizing. You will only have setback one time, the first time. From then on all you have to consider is failures due to work hardening of the neck. I have limited experience with neck resizing but I do not understand how full length resize in a bolt action rifle can match the durability of neck sized rounds.

Gene

[GeneCC]

The next topic was on annealing. They absolutely don't recommend it. They said that the temperature must be kept within certain limits and it cannot really be achieved by the average DIY'er. They said that by the time you even thought about annealing the case necks due to work hardening, the brass is already on it way out the door anyway.

They are right about annealing. We do not have the facilities to test the results of annealing. I've READ that you can soak the bases in a container of water, leaving only the necks to be resized. However I've seen commercial lines for annealing and they do not use water, just time the duration of exposure to heat.

I've personally never done annealing. I buy the brass already annealed. Prvi Partizan and Lapua neck anneal their 7.62x54R brass.

Gene

[normsutton]

I anneal my rifle cases every 3rd or 4th time , especially,on cases I have to form ,

this is one way


NORM