I went to the range today and shot 200  223 rounds that I loaded almost a decade ago.

I forgot that I even had them.

26 grains IMR 4895 with a 55 grain FMJ. It's a compressed load.

Anyway, they shot great, we're very accurate.. but about 65% of the case mouths had splits and or case necks had crackes In them.

I never had this happen before.

The primers weren't flattened at all and I don't think it was a pressure issue; especially with this slow burning powder.

I used Federal LC once fired brass.

I also shot 200 rounds of  24.1 grains of H335 with 62 grain FMJ ; that I loaded a week ago. They shot great too but I had no split case necks with this batch.

Same make brass used but newer..

Thanks.

Age doesn't really do anything to brass.

The conditions that it is stored in can but it doesn't sound like that is the case here.

What does make brass brittle is work hardening. It will need to be annealed every few reloadings to deal with the work hardening that happens during resizing.

Also some batches of brass can just be more brittle than others, no real way to tell.

Oxidation isn't a friend

These were once fired brass only loaded one time.

Since you mentioned annealing, perhaps I should learn how to do it; to get more use out of my brass.
How is it done?  Heat the brass a little with a propane torch?

Another possibility is how you polished the brass back when you reloaded them. Some polishes contain ammonia. The small dose to the brass isn’t such a big deal if reloaded and shot in relatively fast order but, when stored makes the brass more brittle over time. Brasso is the famous example of a brass polish to stay away from because of this issue.

It's a possibility..

I've always used mostly treated walnut hull media

Some brass doesnt get annealed like higher priced match brass. LC is made for 1 firing and made as fast and cheaply as possible.  Scamp machines. produces 1200 cases per minute.

Annealing link

Most dies over work the neck area.  Buying a fl sizing bushing die will let brass necks last longer, by not over working the brass.

I use Rcbs x dies. Can that be part of the problem too?

All brass is annealed in the draw process. Some more then others.   Search here.

Our action stays locked longer then the Galilrife. Opening to soon , under pressure ,  caused case separations. The Win/Nato brass needed longer /hotter anneal to prevent separations lower in the body of the brass.

Or just Google  "dtic mil  annealing"

From search old 1976.The goal of this research has been to clarify why, of all lots tested,
only the conination of Winchester aniunition/Galil rifle produced misfires,
ruptures and circumferential case wall stretching. Research findings point to
the following chain of events:
Case wall rupture results from a coaxial shear stress that rips the
wall asunder in a mechanism similar to static stretching of a tube under load.
Our speculation is that the rupture occurs during retration of the bolt while
propellant gas pressure in the bore is still relatively high.
The reduction in strength demonstrated by Winchester cases is not
apparent from its hardness pattern. There is thus no possibility of predicting
behavioral anomalies from a knowledge of hardness gradients alone.
As is well known, resistance of cartridge brass to drawing depends
upon wall geometry (thickness). The reduction in strength is especially
sensitive to profile or localized wall geometry variations. Of all the case
lots surveyed, the Winchester lots were approximately 20% weaker when compared
against cases derived from other sources. This variance is attributed mainly
to differences in grain structure and size; the grain size found in Winchester
case walls was much larger than that observed in all of the remaining lots
sampled. Sources of (grain size) variance arise from the particular arrange-
ment of process operations utilized in case manufacturing and these operations
are not generally modified to satisfy individual customer's specifications.
The Winchester cases are more likely to prove acceptable if the final annealing
temperature is raised or its duration prolonged to levels comparable with those
normally found at other manufacturing plants.
Therefore, in order to avoid the firing difficulties encountered in
the Winchester/Galil case system, the following two courses of action may be
taken, either separately or together:
a. Increase the resistance to wall rupture by modifying the ammunition
production process.
b. Delay removal of the rifle bolt (change the rifle's timing) until
propellant gas pressure inside the bore has diminished."

I had some .308 brass do that. I loaded once fired R P or Win brass and set it aside about ten years back. After a few years I shot some of it, and over half the cases split at the mouth. Back then I some times used some polish, don't remember which, and these may have had some on them. Either way, I figure I can't reload any of it when I shoot it.

Interdraw Annealing on the Scamp Case Submodule..http://www.dtic.mil/docs/citations/ADA030722

I have a suspicion that the same thing caused the splits in my brass. ( The polished walnut hulls I used then and now)

Ammonia (and ammonia releasing chemical) and brass are a bad combination.

The Brits long ago discovered 'seasonal cracking' in brass in jungle environments.
The decaying plant matter releases enough ammonia to cause long term brass damage.

Even a single exposure of brass can leave enough ammonia between the brass atomic
'grain' boundaries of the metal that cannot be very effectively rinsed off or removed.

It very selectively attacks the boundaries and leads to cracking.
And the more stress the boundaries are under the faster and worse the cracking is.

The stress from loading the bullet and stretching the neck is one of the higher stress locations in a loaded brass case.

Perhaps I should start using untreated media for now on?

I load .30-06 and .308 for cast bullets.  My .30-06 dates from the '40s and '50s.  The .308 is Federal of a later date.  Both are stored in plastic jugs in a shed outdoors in Phoenix.  I have yet to lose a case.

Depends on what the treatment is.

I often use jeweler's rouge in walnut hulls for seriously dirty stuff.
It will polish it up enough to allow cracks or other problems to be seen.

Green Chrome Oxide Compound will also work but takes a little longer.

IIRC at least one company was selling media with Chrome Green.

I have to check out what I have.

There are many chemicals that do not "contain ammonia" but are capable of releasing it when used.

It is attached as a group on a larger molecule but is not present as free ammonia and no ammonia was used in the manufacture.

There is no actual ammonia in Windex glass cleaner.

You can play all sorts of chemical games like having 2(NH2) and not NH3.

I figured neck splits came from over working the brass, like how a spring wears out from excessive flexing.

If you have had a hard time pulling the expander out of a lube 223  neck, this is a sign of over working the brass. Its the main reason necks crack.

They can come from working the brass, but exposure to ammonia (and even ammonia 'like' compounds) can greatly
accelerate the formation of cracks in brass under stress.

The neck tension we use to prevent bullet setback and hold
the bullet in the shell puts a stress on the neck of the shelf.

Ammonia preferentially attacks brass under stress compared to brass NOT under stress.

The stuff I've been using is Lyman Tufnut.

Does it weaken brass?

https://www.lymanproducts.com/msdssheets/

.2 MixturesChemical Name CAS# EINECS# EU Classification
(67/548/EEC)
GHS/CLP
Classification
% w/w
Ground Nut Shell Mixture Mixture Not Dangerous Not Hazardous 90-100%
Iron Oxide 1309-37-1 215-168-2 Not Dangerous Not Hazardous <2%
Highly refined mineral oil Proprietary Proprietary Not Dangerous Not Hazardous ~1%

What is the chemical name for mineral oil?

Other names, similarly imprecise, include white oil, paraffin oil, liquid paraffin (a highly refined medical grade), paraffinum liquidum (Latin), and liquid petroleum. Baby oil is a perfumed mineral oil. Most often, mineral oil is a liquid by-product of refining crude oil to make gasoline and other petroleum products.

ethanol/ alcohol is not good for cartridbe brass.  Dawn has ethanol 5%.

12. Toxicoloigcal Information Iron Oxide: NTP Carcinogen: Known: Yes Anticipated: Yes IARC Category: 3

Just adding my voice to those who have answered, "No" and that what makes brass brittle is work hardening.

Also, wanted to point out that short term exposure to limited amounts of ammonia will have no effect on modern brass.  The phenomenon of ammonia causing brass cartridge cases to crack is known as "season cracking".  British troops in India a century ago stored their ammunition in the stables and it was attacked by ammonia from the decaying urine.  The problem was eliminated by annealing the brass case after it was drawn as annealing eliminates the residual stresses from forming the case.  As all modern cases are annealed during manufacture, it is unlikely season cracking can even happen to modern cases, but small quantities of ammonia, like found in Brasso, and with exposure times of only minutes to hours (as opposed to months) will certainly not cause any problems for modern cases.

Citric acid &  water.  is safer for brass cleaning. Just dont dry it in an oven.

And when you ram a bullet into the case mouth and stretch the brass to obtain neck tension it is put back under stress.

ANY exposure of brass cases to ammonia (or similar compounds) results in some amount of
ammonia behind left behind in the stress areas of the brass.

Modern brass is NOT immune to the problem.

All brass has residual stress.
It is what makes the case head harder than the rest of the case.
It is what creates the neck tension that holds bullets in place.

THIS

Lapua Brass I purchased 10-15 years ago in group buys is still perfectly shiny and waiting to be called into service. I load precision rifle in small lots of 100 rounds to track the number of  reloads. never saw a variance when loading the next 100 rounds.

Interestingly, I've experienced very similar, and not entirely sure.

In my case - brass that had dry tumbled, and loaded up maybe 10 years with basic 55 FMJ loads, H335 I think.  Lot's of split necks upon firing.  Very unusual, none of my more recent loads do this, and I did wonder if age was an issue, even though I wouldn't have thought.

But now that it's mentioned, none of my more recent wet-tumbled brass ever does this; so now I'm curious if 10 years of contact with whatever embedded polish agent that was in the dry media, while under stress of a seated bullet... now I wonder....

Stripper clips in ammo can on climate controlled shelf - for a decade(ish).

Since there have been a couple of other members who posted a similar experience to my own; I'm going to say that it seems that brass exposed to Amonia (polish), does indeed become brittle with age.

That being said, I shot some 9mm loads I made around the same time as the 223 and the cases seem fine.

Military specs are not concerned with reloading, but they are concerned with shelf life.

As a result of all those season cracking and spoilage incidents, the chemistry of the brass and the pre loading conditions, are controlled by specifications. Storage is also controlled.

Many specs call for sealed primers as well as neck sealant. I will have to ask around if we have ever done any long term research on the effects of sealant versus no sealant with respect to the brass metallurgy. We sure did use up a lot of old munitions during my lifetime with no shortage of wars...

I'm also unaware of any reports on the effects of annealing cycles on the brass chemistry based on flame, induction, or salt bath. I'll ask around and see if there is anything to share.

A long time ago, one of the old hands mentioned to me that he would never use unknown brass for long term storage just due to the fact that you don't know what it has been exposed to. I followed his advice...

If you are aware, then the risk is low and do as you see fit. If you don't know the origins, maybe it is best to avoid making large batches for long term storage.

Better to use fresh or known once-fired brass if you plan on letting it sit for many years.

All of that makes perfect sense to me and sounds like sage advice. I wonder from time to time which habits we employ in this day and age that will be frowned upon a decade or two from now. With the knowledge advances we have in metallurgy and chemistry I truly doubt that we are doing anything that will dynamically affect our ammo while in storage to the same degree as practices that were commonplace in the past.

That being said, I envy you guys that can load so much that you have non SHTF ammo that can survive ten years or more on a shelf. At best, none of my reloads could survive more than two years before traveling downrange. I try to balance my range time with my reloading time.

My thinking on the long term storage of ammo for the SHTF scenarios must vary from most in this discussion. I figured that the mil-spec ammo from the Lake City plant (as an example) is one of the few that has been specifically researched and designed to sit on a shelf and still go bang without aberrant effect. That is why I choose to purchase and store sealed cans from such manufacturers in a manner not unlike my Uncle Sam in case this need ever comes up which leaves me a lot more time for working up loads that I want to use now!

Yes, storing something like XM-193 is a better plan than starting with brass of unknown condition.

Sealed necks and sealed primers have their place when it comes to storage in places that have climate swings.

But, if you can't use or don't like factory ammo, just make sure your brass, powder, and primers, have had no questionable origin or exposure and you will be fine.

I routinely tumbled my brass in crushed walnut treated with Brasso.  It wasn't a problem since it mostly got shot promptly.

However, I did put back 1000 or so rounds of a M855 clone about twenty years ago as an "emergency reserve".  Decided to shoot it about a year ago when there were so many sales on IMI ammo.

IIRC, about 90% of them had split necks.  Many of them like that prior to firing.  The bullets were easily removed by hand.  Would have been a disaster having to rely on that stuff....

I now polish my brass using mechanical methods not involving any chemicals at all.