Brass and it's physical properties

[shredder4286]

Howdy all,

Not brand new to hand loading, but still fairly new to the option of Neck sizing brass. I've neck sized a certain lot of WIN .243 cases only 3 times, but a number of them take quite a bit of effort to close the bolt on. It was my understanding that when you approached this point with neck-sized brass, you simply full-length resize, and begin the process over from the start. The weird thing is- once I tested this theory and full-length resized one of the cases- it was harder to close the bolt on than before! I realize that full-length sizing stretches the brass- this case was .005" under max case length. Am I missing any factors that could be causing this?

[Nnobby45]

The nature of the brass is that it looses it's elasticity after a number of firings (your number seems to be three) and doesn't spring back (contract) after firing like it did. That can make extraction or rechambering difficult.

Full length resizing is the solution, but as you run the case up in the die, it gets BIGGER before the shoulder is contacted and gets set back. Adjust the die down until the round chambers easily---but no more.

I'd advise you to FL size all the time. I don't mean screw the die all the way down as some recommend and create more head space than necessary. I mean size just enough for easy chambering. That will keep your brass "trained" so you don't have problems.

Mark a case neck(smoke or magic marker) and adjust die until you see the sizing action stop right about where it contacts the shoulder. Slight shoulder set back is what we're looking for----you may have to adjust the die down a little more. That's for cases fired in your gun.

For cases fired in another gun, keep adjusting the die downward enough for the cases to chamber. Cases may be smalle enough to begin with so they chamber ok if they were fired in a gun with a smaller chamber than yours.

[Nnobby45]

I realize that full-length sizing stretches the brass- this case was .005" under max case length. Am I missing any factors that could be causing this?
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Unless your case length is WAY over max, it will have no effect on chambering. The problem is sizing.

[Jim243]

You need to aneal those cases after the second or third firing. You will start seeing the case necks starting to crack, be careful and put a small light into the case neck and see if you can see cracks.


Jim

[shredder4286]

Full length resizing is the solution, but as you run the case up in the die, it gets BIGGER before the shoulder is contacted and gets set back. Adjust the die down until the round chambers easily---but no more.

I'll give that a try. Thanks

You need to aneal those cases after the second or third firing.

So, does annealing bring back that elasticity to the brass? From what I've read, annealing prolongs case life drastically, but I've never been aware of how it does this.

[Slamfire]

So, does annealing bring back that elasticity to the brass? From what I've read, annealing prolongs case life drastically, but I've never been aware of how it does this.

I don’t anneal. I took one set of LC 308 cases 22 reloads in a M1a, lost more cases in the weeds than due to case neck cracks, and I never annealed any and all were full length resized with the shoulder pushed back about .003”.

I have some bolt gun 308 right now that is up to eight firings and all are full length sized.

Maybe if you are necking up from 223 to 40 caliber, or necking down 45 caliber to 270, the severe working of the brass would cause residual stresses and the stuff would need to be annealed. Heck if I know, I took 100 30-06 brass cases to 35 Whelen, only fired a couple of times but no case neck cracking to date.

What you do need is a cartridge headspace gage. The function is as in this diagram:




This is a 308 gage, just drop the case in and see if it is too long or too short.



This is the difference between Go and No Go, and why you will never get there by following the instructions of “lower the die to the shell holder and give a quarter turn”. Without gages, you just don’t know how much you are setting the shoulder back.



I am not a fan of neck sizing. I know several F Class National Champs, they don't neck size and yet they are winning.

I full length size because I want 100% function. I don't want to beat down my bolt handle. I also get great case life because I don't over size the stuff.

[Nnobby45]

You need to aneal those cases after the second or third firing. You will start seeing the case necks starting to crack, be careful and put a small light into the case neck and see if you can see cracks.

Fred Hunnington, Presidentof RCBS, did a demonstration for a local sporting good store years ago. Using two 30-06 cases, FL resized just enough to chamber, he loaded and fired one 16 times before the case neck split. The other went 18 times.

In the years I've been reloading, split necks have occurred occasionally, but haven't been near the problem as improper (too much) sizing.

I'm for checking cases to find cracks, and I'm for annealing in some cases. Like when you have a limited supply of hard to find brass for older calibers.

[wncchester]

It's no great mystery why necks split, it's cold working. How quickly that happens depends on how much we cold work them each firing and resizing (neck or FL sizing, as such, makes no difference to a neck). If the chamber neck is tight and the die neck is large, the necks won't be worked very much and they will last a long time. Reverse that and they will split much sooner. How it works out for each of us is pure luck, not die brand or the rifle brand or anything else predictable, just luck.

[shredder4286]

Sounds like a whole lot of opinions as to what matters or what works. I'll try adjusting my FL sizing die and will report the results.

[Nnobby45]

It's no great mystery why necks split, it's cold working. How quickly that happens depends on how much we cold work them each firing and resizing (neck or FL sizing, as such, makes no difference to a neck). If the chamber neck is tight and the die neck is large, the necks won't be worked very much and they will last a long time. Reverse that and they will split much sooner. How it works out for each of us is pure luck, not die brand or the rifle brand or anything else predictable, just luck.

Are you honestly trying to assert that some experience case neck splits (I'm talking regular basis) and some don't on the basis of of pure luck?

I don't think so.

Your assessment, minus the pure luck part, makes sense.

And let's not underestimate the effect of that expander ball popping the case mouth back out. This can work the brass more than sizing, and without proper lubing of the inside case neck, the neck gets stretched, worked, and pulled out of alignment.

[Jimro]

Brass "work hardens" as it is smooshed, hammered, or otherwise physically manipulated.

To oversimplify, the copper is "crystallizing" as the metal is deformed, and as the copper attoms arrange themselves into ever more orderly crystals it becomes more and more brittle (crystals are brittle, generally).

What annealing does is thermally excite those copper atoms back into a "chaotic arrangement" and then lock them into that chaotic arrangement by a quick quench.

Jimro

[4runnerman]

Im with Jimro. I anneal my cases every 3rd round. Not only do cases last longer but you will find even neck tension also leads to better group sizes too.

[Jim243]

So, does annealing bring back that elasticity to the brass

Yes it does. To the neck, you only aneal the neck of the case.

But I also agree you may not be bumping the shoulder back enough to get your cases to the right size.

Jim

[brickeyee]

Are you honestly trying to assert that some experience case neck splits (I'm talking regular basis) and some don't on the basis of of pure luck?

It is pretty much luck how well any individual die matches any individual chamber unless they are cut with the same reamer very close together in the reamers life.

A factory starts with e new reamer at the larger end of allowable tolerance, ad uses it until it wears to the small end.

The die makers do the same thing.

How any chamber and any die mach up is a crap shoot within the allowable tolerances.

[243winxb]

Full length resizing is the solution. No annealing needed. Brass "work hardens", true. For long case life, buy bushing dies that do not over work the neck area. Its possible to not use an expander with bushings. Have 18 loadings on my brass. modulus of elasticity- Cartridge Brass-
Material is 70 copper/30 zinc with trace amounts of lead & iron , called C26000. Material starts to yield at 15,000 PSI when soft (annealed), and 63,000 PSI when hard.
Material yields, but continues to get stronger up to 47,000 PSI when soft, and 76,000 PSI
when work hardened. Modulus of Elasticity is 16,000,000 PSI. This means to pull a 1.000 inch long strip to 1.001 inch long induces a 16,000 PSI stress.
So if you pull a 1.000 inch strip to 1.005 inch long, you get about 76,000 PSI, which is the max obtainable.

[shredder4286]

RESULT: I ended up turning the FL sizing die about 3/4 turn past where the instructions tell you to put it. As expected, they did chamber much easier. The only downside: a hair larger groups w/ those which were FL resized over the neck sized cases.

[wncchester]

"Are you honestly trying to assert that some experience case neck splits (I'm talking regular basis) and some don't on the basis of of pure luck?"

Well, we all get neck (or body) splits eventurally no matter how we resize, don't we?

Is it "pure luck"? Yeah, that's exactly what I assert. Brickeyee understands and he explains it well enough if you didn't get what I actually said. What do you call it when the cause of splits is the difference in diameters of what we may get from any off-the-shelf sizer and chamber? It sure ain't skill!

You should know that the expander ball, of itself, plays no meaningful part in the neck's cold working. The sizer has already made the neck too small and the expander can do nothing that won't continue even further during bullet seating. ??
___________________________________________

"RESULT: I ended up turning the FL sizing die about 3/4 turn past where the instructions tell you to put it."

You need to know that the full range of headspace, max to min, of most bottle neck cartridges is about 6 thousants. A full turn of a die equals about 72 thousanths so your 3/4 turn moved the die about 54 thou, that being some 9 nine times more than the full range of permitted headspace!

Once a case has fully entered a die it can't go any further so the flex in your press had to accommidate the additional stress. But, by jamming the cases in so deep, you may have set the shoulders back too far and that will set you up for excessive case stretching and the potential for a dangerous head seperation. If not, it's only pure luck that your die and shell holder actually matches your chamber length.

All any die instructions can tell us his how to get into the right ball park. A few thousants matter, no one can properly adjust a sizer by following any rote plan; the dies, shell holders and presses vary too much for that to work - except by accident!

[davery25]

how do you move the shoulder back with the die? is it just screwing the die in past the manufacturers recommendations?

Also how do you actually measure how far you've moved the neck back without a no-go gauge?

[shredder4286]

A full turn of a die equals about 72 thousanths so your 3/4 turn moved the die about 54 thou, that being some 9 nine times more than the full range of permitted headspace!

Ok, I don't think it was quite 3/4 of a turn, but I probably should have turned the die in smaller increments. I pretty much adjusted it, and they chambered easily...

[F. Guffey]

#18
davery25
Member


Join Date: October 4, 2011
Posts: 25 how do you move the shoulder back with the die? is it just screwing the die in past the manufacturers recommendations?

Also how do you actually measure how far you've moved the neck back without a no-go gauge?



Skill, combined with technique AND methods, that is what I do, I use the companion tool to the press, the feeler gage, to reduce the length of the case from the head of the case to it’s shoulder I raise the case off the shell holder deck, not much use for a reloader to know but when forming cases for short chamber it is the feeler gage or mindlessly grinding of the shell holder and or both.

To increase the length of the case from the head of the case it’s shoulder I increase the gap between the top of the shell holder and bottom of the die, no wild guestimates of a fractional of a turn or converting degrees to thousands, after making the proverbial wild guess the guesser could use a feeler gage to verify the wild guess, but it they got into the habit of verifying, why wouldn't the go straight to verify to make the adjustment?

As to measuring, I make tools our of any and everything, I make tools for measuring the length of a case off the shoulder and or bullet, things that are tapered, round and create a cone does not hang me up, those that get
hung up on such matters refer talk in lofty terms like ‘datum line’, to me the datum is not a line, it is a round hole/circle, if I do not have ‘SAMMIES’ specs I make them up, after all, it is my chamber, my die, my case.

“Without a no-go gage?” If a reloader knew the length of the chamber before starting to reload for their chamber the reloader does not need a go, no or beyond gage, if the reloader was familiar with the use of gages the reloader could make gages, or convert some gages to a gage that would serve as a go, no and beyond gage, If a reloader had a field reject gage the reloader could use the field gage to measure the length of the chamber from the shoulder back to the face of the bolt in thousands.

I determine the length of the chamber first, then form, others chamber, fire to form then get hung up on explaining why everyone is wrong and they are correct. Has something to do with “a case is not fully grown until it has been fired 5 times, for me a case that has been fired 5 time is a five time fired case and full length sizing to start over is not an option

http://wordinfo.info/unit/1/ip:3/il:B

F. Guffey

[F. Guffey]

Shredder, you could have increases the distance the die was screwed down an additional 3/4 turn, before I punished my equipment I eliminate bad habits, bad habits? Taking advise from the Internet that is repeated over and over and over etc., etc.. The first one that comes to mind sounds something like “Chamber a round, pull the trigger to fire form, then neck size 5 times, THEN, when the case becomes difficult to chamber start over by full length sizing” HOW IS THAT POSSIBLE? Then there is the “A case is not fully grown until it has been fired 5 times”

I do not know what press, die and shell holder you are using, there are times the press wins, there are times when the shell wins, I do not find an advantage to sizing tuff cases, with a feeler gage the amount of stress, strain and flex can be measured when measuring. Put another way, a case can be tuff enough to refuse sizing even when the die is screwed an additional one turn, for those than can keep up if the case can not be stuffed into the die with an additional turn the press flexes, binds or bends. In the old days strain/deflection gages were used when comparing the strength of presses, in the perfect world cases used when testing the strength of a press 5 time fired cases were not used. But, when comparing the effort, effect and difference between sizing a 1 time fired cases and 5 times fired cases a few reloaders could draw a conclusion, sizing a 5 time case to start over is a bad habit.

F. Guffey

[ligonierbill]

Since the OP asked about physical properties of brass, this old metallurgist has to weigh in. First, work hardening. Metals are so versatile because of the bonding between the atoms, literally a "metallic bond" that is described as a shared cloud of electrons. This as opposed to an ionic bond like, say, salt. Salt doesn't bend very well. Metals do form crystal structures, in the case of brass it's labeled face centered cubic, a very simple form. A piece of metal is not a single crystal, rather an array of tiny crystals called grains. A metal can deform elastically, meaning it will come back to its original shape when the stress is released, or plastically, that is permenantly. Plastic deformation generally occurs through the movement of line defects known as dislocations, although a bulk shearing called twinning can also occur. When the dislocations move, they can get hung up on defects in the crystals, including each other. This results in stress within the crystal, making it harder and more brittle. Annealing relieves this stress. In a perfect shooting world, the case would match the chamber exactly. When the powder is ignited, the case and chamber would expand slightly, but unless the pressure is excessive causing excessive expansion of the chamber, the case will simply be pressed against the wall of the chamber under hydrostatic stress and return to its original dimension (perfect world). So, there would be only hydrostatic stress on most of the case, no shear stress to cause deformation, except for one place, the neck. The end of the neck is not supported by the chamber, so it can flow and elongate slightly. It also gets a little thinner. Each time we reload, whether neck sizing or full length resizing, we work that neck and maybe trim off a bit. Brass does work harden, but not as much as, say austenitic stainless (why it's a pain to machine). So cases can take a number of resizings without annealing, unless something is off. An off spec chamber or pushing the shoulder back too much increases the amount of deformation and work hardening each cycle. Not only that, but the deformation will occur in places other than the neck. Some folks hate the belted magnums because the case can stretch (deform plastically) just ahead of the belt leading to premature failure. Bottom line is that case necks crack due to thinning as well as work hardening. I have never annealed cases, but I notice that new Lapua cases are annealed at the neck, so maybe it's not a bad idea. And of course, keep pressure within reason and don't push those shoulders back much.

[Slamfire]

I have never annealed cases, but I notice that new Lapua cases are annealed at the neck, so maybe it's not a bad idea. And of course, keep pressure within reason and don't push those shoulders back much.

I think all factory rifle cases get a shoulder/neck annealing step at the end, to prevent stress cracking. I believe this is discussed in books by Phil Sharpe.

Consumers like shiny cases so factory cases are tumbled to remove the evidence, but the US military leaves the color layer on.

[brickeyee]

Many cases are annealed multiple times during drawing and forming.

They all start as disks of brass that are on the soft side.

All the drawing and forming steps work harden brass enough that annealing during manufacture can be required between draw-form steps.

Steps are taken to preserve things like the hardness of the case head.

[243winxb]

Annealing in special chambers with certain types of gas will not leave any residue on the brass. If i remember correctly, no oxygen allowed.