Does the case only work harden at the neck and shoulder ?

[Metal god]

Now there's a catch to this . I'm not only speaking when sizing the case . I talking about when the case is fired as well .

Here's a little background to the question :

I have what I believe to be some softer LC-14 308 cases . These were once fired by the military and bought by me from the local range the military uses . The primers were crimped and I had to remove the crimp before loading them . So I know they were once fired . The thing is many of the had clear brass flow into the ejector hole as well as extractor marks .

Disregard the arrow but it does point out the extractor mark but if you look at the other case you can clearly see the ejector mark/circle around the 1 and that's not even one of the worst ones . These are once fired and many of the primer pockets are already stretched out . That primer seated on the upper right had virtually no resistance when seated .

With out going into great detail these cases can't handle the same charges that my Lapua or LC-LR cases can with virtually the same case capacities . The LC-14 cases get sticky bolts 1.5gr less in powder charge and 100+fps less using the same components . I've had these cases for a year+ and I've loaded 300+ of a 1k count lot . I've observed a few things that has lead me to believe these cases are just softer then maybe what's best .

So now to the heart of my questions . Does the head and web of the case also work harden as the case is fired then resized then repeat ? I guess my over all question is , will these cases always be soft or will the firm up over time and use ? most of the ones I've fired so far have smashed that ejector circle back down to where you almost can't tell it was there before . The extractor marks are still there though .

FWIW I've been using a small base die to size these cases . I had been getting some resistance closing the bolt on a FL sized case regardless of how far I bumped the shoulders back . After painting the case with a sharpie . I found that the resistance was the case rubbing at the web area . I bought and used the small base die and that solved that problem .

Anyways about 20% of these cases have the ejector marks on them and everyone of those I tested had loose primer pockets . I tossed those and kept the rest but I believe they are all still softer cases .

I do have a light-ish load that shoots well using these cases so on the whole it's not a big deal that they are soft but all this got me to thinking about what areas of the cases actually work harden and would these cases ever firm up to handle heavier loads with out stretching out .

On a side note , does anyone know what the little dots on the headstamp indicate ? I have many LC cases in both 5.56 and 308 . Some of the years have those dots while other years don't . As far as I can tell , The years that DO NOT have the dots seem to shoot and or load better .

 

[F. Guffey]

FWIW I've been using a small base die to size these cases . I had been getting some resistance closing the bolt on a FL sized case regardless of how far I bumped the shoulders back . After painting the case with a sharpie . I found that the resistance was the case rubbing at the web area . I bought and used the small base die and that solved that problem .

Yes, that small base die is such a big problem solver I am surprised it is not the only die a reloader needs. I have small base dies, I do not use them but I have them 'just in case'.

My shell holders prevent the small base die from sizing the base of the case.

The one thing the shooter does not want is a case head coming apart because it is hard and brittle. My favorite case is the one that expands.

It seems many years ago I purchased what I thought were magnificent cases. I tumbled the cases, separated them in groups of 20 and started loading and firing them and they were magnificent cases until someone said! They had a recall, seems they decided to save money by reducing the numbers of times they annealed the cases during the manufacturing process.

I moved the cases to the collectable drawer, I have found additional cases among cases I have received from old friends, they shot those cases over and over and they had no hesitation about going straight to the max load, again, they were magnificent cases and I doubt all of the cases were compromised.

F. Fuffey

 

[T. O'Heir]

Work hardening is about the neck being repeatedly sized and expanded. The primer pockets will stretch over time. There's no fixing oversized primer pockets though. The cases will usually crack long before the pockets get too big.
LC-14 308 cases were primarily made for and used in MG's, not rifles. MG chambers are looser than rifle chambers. Aids feeding under the high heat generated.
A small base die does not and will not size the case head. An SB die only sizes the case about 5 thou more than a standard FL die. You really shouldn't need SB for .308.

 

[RC20]

What you are describing is over loaded cases.

Why they are too hot, impossible to tell.

I don't believe it has anything to do with soft.

I have created a few of those type, FL won't resize and primer pockets loose.

 

[243winxb]

Dots- Some US GI cartridge cases are run on SCAMP (Small Caliber Ammunition Modernization Program) lines. This is HIGH speed cartridge case making equipment. Several lines of SCAMP machinery may be used to run cases thru out the year, or on the same lot/year of ammo. Those dots identify which SCAMP line they came off of.

 

[Metal god]

What you are describing is over loaded cases.

Agreed

I don't believe it has anything to do with soft.

I disagree

The avg case capacity of 10 LC-14 was 55.12gr of H2o

The avg case capacity on 10 LC-12lr was 54.97gr of H2o

That's a .15gr difference and yet I can load the LC-12 cases to a charge weight 1.5gr larger then the LC-14 cases with no pressure signs . Meaning 43gr of IMR-4895 pushing a 168gr BTHP shows no pressure signs in the LC-12-LR cases . While 41.5gr in the LC-14 cases gives me sticky bolt lifts and is over 100fps slower then the 43gr charge in the other cases with both having virtually the same case volume .

If not soft cases what would be your reasoning for that to be happening . I'll admit I do not have the tools to test the hardness of the cases but it seems to me the LC-14 cases are clearly showing "signs" of over pressure when they're likely well below max pressure based on the charge and velocities I'm getting . Wish I had QL that may help clear things up a bit here .

Thanks 243winxb , that's interesting and may explain why It appears to me at least the cases with the dots are not as good as the ones with out .

 

[F. Guffey]

The avg case capacity of 10 LC-14 was 55.12gr of H2o

The avg case capacity on 10 LC-12lr was 54.97gr of H2o

Therefore? Where is the logic? Are you using deductive reasoning?

I understand, when I say I am the only reloader etc. et. that does this and or that it drives all of the reloaders to the curb. Not my problem, Reloaders are too selective and they remind me of 'siders'.

You assume the case is thicker because it is heavier, I have always said that could be a half truth and it if is a half truth we would have to add another factor.

F. Guffey

 

[Mike Irwin]

"Does the case only work harden at the neck and shoulder ?"

To answer the original question, no. Firing does cause some small degree of work hardening, but it's minuscule compared to what a resizing die does.

 

[dahermit]

There's no fixing oversized primer pockets though.

Actually, not true. The rod that is part of the RCBS Primer Pocket Swag is cup-shaped. When a case with an over-size primer pocket is subjected to that tool, the cup-shaped rod pushes down against the web of the case and the brass extrudes inwardly due to the "cup".

I have used that RCBS tool to tighten the primer pockets on my .308 Winchester cases as well as my .22 Hornet cases. It resulted in saving my Federal Target .308 cases that were subjected to just-a-tad-too-warm-loads and likewise those weak little .22 Hornet cases.

I heard about that method of tightening primer pockets years ago (it was not my discovery) and was skeptical. However, I found that to my surprise, it worked.

 

[tangolima]

Metal. If you have a chance to review the manufacturing process of the brass, you will see it has multiple annealing steps. But towards the end of the process, such annealing steps are to purposely avoid the head and web, and even everything below the shoulder. Those parts are let to work hardened, so much so that a fresh brass must be able to contain the hottest load possible. So they are not soft to begin with.

They will be further work hardened during their service life. But it is very rare that they become so brittle that they split. They probably will eventually if the other parts don't fail first.

-TL

Sent from my SM-G930T using Tapatalk

 

[F. Guffey]

Those parts are let to work hardened, so much so that a fresh brass must be able to contain the hottest load possible. So they are not soft to begin with.

Long ago and forgotten by reloaders there was a process for determining case head expansion. At the time there were rules like the case had to new and factory loaded, the reloader was required to measure the case head diameter before and again after firing.. It was suggested the reloader use a bladed micrometer. As always there were problems with the information, most reloaders could not determine where the case head was to be measured.

Case head expansion? By how much? It was suggested case head expansion for new/factory loaded ammo should be .00025. Now? Why would I bore you with too much information?

Reloaders assumed the .00025: case head expansion applied to every firing of the case so it was assumed 4 firings would equal .001" case head expansion. That is not what happens, as the case head work hardens the expansion of the case head is reduced.

The cases I purchased from the Iron and Metal yard came to me without instructions, they were cheap and straight from the arsenal. I did not need them, I could have thrown them away without missing them. The cases are the only cases I have ever been warned about being brittle. Again, I am the fan of cases that expand at the case head, the alternative to case head expansion is Catastrophic failure.

F. Guffey

 

[F. Guffey]

most of the ones I've fired so far have smashed that ejector circle back down to where you almost can't tell it was there before . The extractor marks are still there though .

What would have happen had you indexed the case? I have suggested the extractor did not support the case head, and then there is a chance the extractor protruded from the face of the bolt, I know; everyone is so confused but I am the fan of 100% bolt face support.

Some shooters have innies and other shooters have outties when it comes to push feed extractor protrusion. If the shooter wants to know which look at the case head.

F. Guffey

 

[JeepHammer]

The 'Dots' are die marks that tell which press die set they came out of.
Same brass goes into the dies, dies made to the same specifications,brass heat treated the same way both before & after it comes out of the dies.
If you had a quantifiable difference between dots & no dots, it probably had more to do with the base material that came in the door (coil brass).

There are a TON of half truths, non-truths & outright lies about brass/hardening.
The shock alone will work harden brass, pressure flexing will harden (stress) brass, the surface of the case head is usually harder than the core of the case head, softer inside than outside.
The area around the flash hole is usually harder, many flash holes are punched, not drilled and the punching process hardens the area local to the hole.

Having pointed this out, I'm not sure it matters much since there is very little you can do about it without great trouble & a lot of tedious testing...

Mr. Guffy pointed out brass is heat treated (annealed) several times during the manufacturing process, and I know this to be true, I've seen it first hand at different ammo plants.
Sheets are punched for discs, then annealed back to dead soft.
The discs are punched for 'Cups', then annealed back to dead soft.
The case body (Tube) is formed in a punch press, ANY excessive stress and the 'Cup' will split when being punch ('Drawn') out into a tube.

I know this first hand since I destroyed a LOT of brass trying to produce a tube blank...
The heating process is ceramic media that is baked, takes time to properly anneal the brass to dead soft.
There is a reason I stress a TIME component, along with maximum temp control for precise annealing & grain structure for proper working of the brass.

After the tube blank is formed, the machining processes begin, the tube is checked for concentric, punches deflect off center under several tons of force and produce uneven case wall thickness, ones that pass get rims cut into them, then the top, what will be the shoulders & necks get annealed again for the shoulder/neck shaping.
This is bend forming, not forming in a 'Plastic' state, so heat treating/annealing doesn't need to be nearly as precise.

Shoulders/necks are formed, and the necks are usually annealed again.

So...
It's a fairly complicated process. Lots of machining, punching, bending, etc. And all the different zones have differing degrees of 'Hardness'.
From how sharp the 'Punch' or drill was that made the flash hole to a dozen other vairables.
Chasing surface to internal hardness differences, case wall differences, etc will drive you crazy!
(Ever try to hit the EDGE of a sectioned case wall with hardness tester punch? Mind numbing!)