I'm not a hoarder , but I do keep some components tucked away for a rainy day. Just curious as to how long brass can lay around before it starts to age harden ?

longer than you need worry about

Good to hear. So 20-40 yrs. no problem?

I do not believe it hardens with age unless exposed to the elements. It WILL harden w/ use.

If you have ever had Ammonia "Vapors" in your house, you might have a problem. That is any kind of Ammonia from floor cleaners to window cleaners to Gun Cleaning Products.

If no Ammonia, then I believe you will find it kind of depends on the specific Lot of Cases. Some do fine for many years and some just seem to Harden.

But, assume they are good and run a few Extended Life Tests on 6-10 randomly picked cases from your Lot. Load, fire, reload, fire, etc., until you get a Case Failure. If " ANY " of them have a tiny Pin Hole appear in the Case Wall, you had Ammonia vapor reach them whether you were aware of it or not. And if the Pin Hole does show up, then you will need to check the Chamber to make sure it did not get a tiny Crater blown into it.

Always something to keep us guessing.

An experienced reloader told me once that cases slowly harden with age. However, it's impossible to say how much and how fast.

Let's look at it another way: I've shot ammo that was 40-50YO that went bang and the case, to a casual inspection, appeared to be fine.
One would think that if that ammo stayed good, then empty cases should be fine for at least that long. If it's 1X cases, and you're really annal, you could use one of the techniques for washing the cases inside and out before you stored it.

Cartridge brass will not age harden to any significant degree if at all.
The problem with brass is 'stress corrosion cracking' .The stress is usually there from improper neck annealing. The major corrodent is nitrogen compounds .Ammonia cleaners is a good source of that but it can be the nitrogen compounds generated by thunderstorm ! The Brits found ,back in the early days of cartridges, a problem in the rainy season in places like India .Thus the term 'season cracking'.

I got some 30-06 1918 FA from my great grandfather, kept inside and there are no problems other than age darkening. I got some remington 7x57 from a friend that was produced in the 60-70s and was kept in an uninsulated garage in northern idaho for at least 20 years, out of a box of 20, only three necks were not split.

Take it for what it's worth ;

I have some .380 cartridges I loaded 25-30 years ago , stored inside the safe inside plastic ammo boxes

90 grain bullets Unique 4.2 grains and Bullseye I believe is around 3.2 3.5 ?.

Been awhile since I looked ,anyway upon firing EVERY CASE SPLIT !. Those were good brass cases with

maybe 2-4 reloads on them . Now go figure I've got 7mm Rem Mag reloads that are 40 Plus and some near max

loads .

Typically 1 -3 split necks out of every 100 don't know how many reloads but more than a dozen ,that

I'm positive of !. I never annealed back then nor did I care , because

components were cheap and readily available !. I've still got primers with the prices on the boxes

try $0.35 -0.65 per hundred !!!.

Powder deterioration could be the culprit or at least help aggravate the brass hardening condition !.


Solid Solution Alloys. The most compatible alloying elements with copper are those that form solid-solution fields. These include all elements forming useful alloy families (Zn, Sn, Al, Si…). Hardening in these systems is great enough to make useful objects without encountering brittleness associated with second phases or compounds.

Cartridge brass is typical of this group, consisting of 30% Zn in copper and exhibiting no beta phase except an occasional small amount due to segregation, which normally disappears after the first anneal. Provided that there are no elements such as Fe, cold working and grain growth relation ships are easily reproduced in practice.

Age-hardenable Alloys. Age hardening produces very high strengths, but is limited to those few copper alloys in which the solubility of the alloying element decreases sharply with decreasing temperature. The beryllium coppers can be considered typical of the age-hardenable copper alloys. Other age-hardenable alloys include C15000 (zirconium copper); C18200, C18400 and C18500 (chromium coppers); C19000 and C19100 (copper nickel phosphorus alloys); and C64700 (copper nickel silicon alloy).

By combining cold working with heat treatment, higher strengths can be obtained than can be achieved by either cold working or age hardening alone. Beryllium copper illustrates well the effects of heat treatment and cold working: in the soft, solution treated condition, the tensile strength is about 500 MPa, solution treated and aged, about 1000 MPa, and solution treated, cold worked and aged, about 1400 MPa.

Some age-hardening alloys have different desirable characteristics, such as high strength combined with better electrical conductivity than the beryllium coppers.

Just like your arteries, your cases will harden with age. Unlike your arteries, you can restore the ductility of the case necks by annealing them. This is another subject altogether and one that everyone seems to feel compelled to chime in on whether they have a clue as to what is is or how to do it right or not.---Maybe you should just buy brass enough for immediate use.