Brass hardeing with age

[dickn52]

This is 75 years ago. Pre-WWII ammo. Makes a nice collector item.

 

[wapiti25]

I have had 1960's/1970's (32 win spl) ammo crack in the original box

 

[LHSmith]

I've googled this once before after getting into this debate and I found the same explanation from another google search that claims the following reason for "season cracking" or stress corrosion of brass cartridge cases: it's corrosion formed inside the case due to ammonia and oxides of nitrogen due to aging of smokeless powder. This was found in ASTM International publication STPA64 "Protective Resin Films In Cartridge Brass" based on studies at Frankford Arsenal.

 

[savagedasher]

I've googled this once before after getting into this debate and I found the same explanation from another google search that claims the following reason for "season cracking" or stress corrosion of brass cartridge cases: it's corrosion formed inside the case due to ammonia and oxides of nitrogen due to aging of smokeless powder. This was found in ASTM International publication STPA64 "Protective Resin Films In Cartridge Brass" based on studies at Frankford Arsenal.

Finally we got the problem solved. Good job
Larry

 

[Webster]

"I think a few bad cases get past inspection at the factory. "

That's it???? That is the best you can come up with??? NO. I do not believe you. How do you explain the fact that I have seen several {at least 3} boxes of old ammo and absolutely every single cartridge had a split neck. They were from the 40's mostly, some from the 50's...and no, I wasn't trying to use them, yes, all my brass that I use is new...but I saw them never the less. And you are telling us that the factory QC dept. "missed" every one of these cases???? Zero chance dude. Come up with a better excuse if you want to sell this story.

 

[Webster]

I never said all the bad cases were ones that got thru factory QC. I was only pointing out that there are some factory defects. If all cases got hard with time wouldn't all old cases fail, of course they don't. As far as I know case necks can only crack when they are cold worked beyond some point or stress corrosion takes place. Cannot think of any other mode of failure.

 

[RW]

I never said all the bad cases were ones that got thru factory QC. I was only pointing out that there are some factory defects. If all cases got hard with time wouldn't all old cases fail, of course they don't. As far as I know case necks can only crack when they are cold worked beyond some

 

[RW]

Wow!! I feel like a guy who threw a cat in a pit with a bulldog! I myself was just wondering if the condition exists! I my self wasn't to concerned about what causes it, But I do surely Thank everyone for their expertise and knowledge of the condition!! I just had some old brass hanging around and was concerned as to when brass gets hard with age? With brass hard to come by it might come to be a problem down this road we are on with a shortage of components. I do appreciate the help from you members that are way more knowledgeable than myself. Ron

 

[impalacustom]

You have to remember you don't know where this brass lived it's entire life. As stated above, the gunpowder, which contains amines and nitrates, (it is it's own oxidizer after all) can cause it. Pure water will cause it. When I was designing heat exchangers we would always use a sacrificial anode to make the exchangers last longer. There are a LOT of variables and you can't prevent them all. Here is a scan of my book explaining it. The important part to look at is the Venn diagram and Table 1. Another thing to think about is Galvanic Corrosion, where 2 dissimilar metals create corrosion.
Best rule of thumb is if you don't want to ruin brass that could be a collectors item, don't shoot it, it might crack on it's own but at least it has it's original bullet.