How a cartridge case should wear out.

[BattleRife]

Bruce,

Any idea why factory loaded ammo would crack at the neck?
I have a box of UMC 25 Remington from circa 1906-10, the necks are cracked on quite a few of them. I suspect a chemical reaction with either the copper of the projectile or maybe the powder.

I have been trying to find an original 41 Swiss round for my collection and notice many of them are cracked from the black powder reacting with the copper (or so I am told).

Cracking of a loaded brass cartridge case is almost always due to a phenomenon called stress corrosion cracking. It occurs when you have 1) a susceptible material, 2) a corrosive environment, 3) a sustained stress. SCC was actually discovered in ammunition, when the British occupiers in India found that their cartridge cases cracked every monsoon season.

70-30 cartridge brass is susceptible to SCC when exposed to ammonia or its derivatives. A loaded cartridge case is always under high stress at the neck, where it holds the bullet. Any exposure to ammonia (which is remarkably common, in everything from window cleaner to cat piss) may cause a cartridge case to crack within a few hours. Annealing the case helps quite a bit, which is why all modern brass is annealed before loading.

 

[Short Knife Johnson]

Every few firings depending on the brand of brass is never a bad idea I find. some of the exotic stuff that costs around $2 each and up you don't want to be losing to premature wear. Even my .45-70 and .45-90 will be annealled every 3 firings or so. It's easy to do, and well worth the trouble for the extra case life you will get.

 

[Noel]

Cracking of a loaded brass cartridge case is almost always due to a phenomenon called stress corrosion cracking. It occurs when you have 1) a susceptible material, 2) a corrosive environment, 3) a sustained stress. SCC was actually discovered in ammunition, when the British occupiers in India found that their cartridge cases cracked every monsoon season.

70-30 cartridge brass is susceptible to SCC when exposed to ammonia or its derivatives. A loaded cartridge case is always under high stress at the neck, where it holds the bullet. Any exposure to ammonia (which is remarkably common, in everything from window cleaner to cat piss) may cause a cartridge case to crack within a few hours. Annealing the case helps quite a bit, which is why all modern brass is annealed before loading.

Thanks for clarifying! If nothing else it makes them easy to take apart to try and duplicate the loads.