Does rifle/pistol brass deteriorate significantly over time?

[8mmFan]

Was reading the interesting thread earlier on tin/lead, and a quote there caught my eye:

"I have some boolits stored around here that are over 5 years old and I have yet to load them. They do not deteriorate with age although the same cannot be said of the brass. Some of the tumble cleaned stuff needs a polishing prior to reloading only for the tarnishing received over time even if kept in airtight plastic containers."

I guess I didn't realize that brass deteriorates over time, other than with "work hardening." Is that the case? Does it? I have a fair amount of 30 y/o brass that I am counting on using at some point.

Thanks,

8mmFan

[Dusty Bannister]

Tarnish is not corrosion. Tarnish is the oxide that forms on the surface. Cosmetic.

[M-Tecs]

Cartridge brass does not precipitation/age harden like some other material.

Some chemicals like ammonia can do damage known as stress corrosion cracking.

Brass also work hardens. Using wax when tumbling tend to reduce or eliminate tarnishing. All that being said brass doesn't go bad from age. I am still shooting brass from the 40's and 50's.

I do anneal necks for work hardening and to maintain seating pressure.

See post one below.

https://forum.accurateshooter.com/threads/age-hardening.3941787/

[Winger Ed.]

Brass plumbing fixtures & fittings and various motor bushings & bearings seem to do OK over time.
I figure cartridge cases should too.

[8mmFan]

Perfect. Thanks guys.
8mmFan

[pworley1]

I shoot a lot of Lake City brass with head stamps going back to the 60's. It seems to do fine.

[Hick]

Twin Cities military 30-06 from '53 is still going strong too

[JimB..]

I have brass tumbled with pins stored in ammo cans. There is some darkening as the years pass, but at a decade it’s still perfectly loadable. I’ve never put O2 absorbers in a can to see what that does over the years. Maybe I’ll set it up with 2qt mason jars so I can watch for changes.

[Sasquatch-1]

I have some pistol brass (.38 spl and .44 mag) that I have been using since the mid to late 1970's. I am starting to get case splits, but this is from stress fatigue and not age. Some have been loaded up to fifteen times or more. I do not anneal the brass. Also, all of these are nickel plated.

[ioon44]

I have some .45ACP WW2 brass in my practice ammo, I have no idea of how many times I have loaded and shot this brass, just keeps on working.

[JSnover]

Moisture and fingerprints (and mice if they're able to chew through the container) are your worst enemies for long term brass storage. As long as they're clean and dry they might darken a bit but there won't be anything wrong with them.

[openbook]

Tarnish is the oxide that forms on the surface.

In piping applications this is referred to as a passivating oxide layer and is part of the materials science behind high-end machines. I was curious and looked up "tarnish" on Wikipedia. It uses similar words and explains the concept:

"Tarnish is a surface phenomenon that is self-limiting, unlike rust. Only the top few layers of the metal react. The layer of tarnish seals and protects the underlying layers from reacting.

Tarnish actually preserves the underlying metal in outdoor use, and in this form is called patina. The formation of patina is necessary in applications such as copper roofing, and outdoor copper, bronze, and brass statues and fittings." https://en.wikipedia.org/wiki/Tarnish

Unlike rust, which is flaky and continues to remove material indefinitely, tarnish is stable and protects the underlying metal.

[Der Gebirgsjager]

I reloaded these in 1988 and now they look a little gungy, but will fire reliably, polish up nicely and be reloaded again.

312128

DG

[atr]

I'm still using GI brass stamped in the 40's! Good stuff.