What the hell happened

don't know they say if you leave powder in the plastic hopper too long it will cause the plastic to react with the powder if the bullets were not sealed well and stored in a plastic case maybe the same thing just a guess
 
It looks like some sort of a stress fracture that over time corrosion found its way into the micro cracks. $64,000 question is why? I would not have been surprised if at the web area but on the shoulder is perplexing. Old military stuff that was corrosive primers and not cleaned off?
Stress forces microscopically weaken the metal enough that the corrosion agent(s) work better/faster along the stress lines. Similar things happens with steel. Were they all shot in the same rifle? Same caliber or are there others? The brass flow while fire forming to a chamber might be enough to create this pattern. Can you estimate how old the reloads are ?
 
I've seen this a couple of times, and there can be multiple reasons for it:

*Powder degradation that creates nitric acid and reacts with the brass and first shows in the thinner areas.
*Cases that were cleaned or polished with an ammonia or acid based product and not properly deactivated afterwards.
*Corrosive priming once used and if not properly cleaned afterwards, reloaded and stored in humid environments.
*Combinations of the above.
 
Stress forces microscopically weaken the metal enough that the corrosion agent(s) work better/faster along the stress lines. Similar things happens with steel. Were they all shot in the same rifle? Same caliber or are there others? The brass flow while fire forming to a chamber might be enough to create this pattern. Can you estimate how old the reloads are ?
Same rifle, and it's just his 308.
 
Carbon ring is the answer to everything...
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I was going through some of my father in laws reloads and found this. In all my years reloading I've never seen anything like it. Sure would like to know what caused this.View attachment 284828View attachment 284829View attachment 284830
Weak brass; here's the same story from a "major" brass manufacturer this is recent with new unfired .223 brass, I won't name the company because they made it right with me and corrected the problem on their end. I had about 1500 rounds of this stuff.

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Looks like deterioration of 20 YO plus?, slightly compressed 4064 (long for diameter grains). Upon forming the shoulder longitudinal stress fractures (compression) were formed making for a gateway for corrosion for products of powder deterioration like nitric acid; blue-green copper oxide formed. Long term warm storage would speed deterioration.

My thinking:

The "stress fractures' would be formed at the point where the shoulder was formed from compression of brass at junction of body & shoulder. These tiny little cracks would be formed in a ring where the body was bent to form the shoulder and deterioration stuff penetrated there making for the blue/green stuff (copper oxide) erupting thru the case. About a 20 * bend stretching the outside & compressing the inside, same location in each round.

Above the junction of body & shoulder the stress fractures would run parallel to the axis of the case. Outside brass looks clean & shiny especially extractor grooves indicating interior chemical/corrosion action. Powder deterioration is an on-going process and compounds like calcium carbonate are commonly added to smokeless powders to ****** the deterioration.

When large amounts of powder is hoarded deterioration of same is a possibility but there appears to be no set short term time limit as temperature is a big factor.

In the mid 60's I used surplus H4831 apparently salvaged from pull down 20mm rounds & that stuff might have been 20 years old. Red & yellow cardboard box for less than $3.00 per pound. Many pounds of this were used in .270's.
 
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Nitric acid like they said. Or something with ammonia was used in the sizing/loading process. Crazy how it burned thru in almost the same pattern in each round. Has to be an interaction between the powder and bullet base
 
Yes the bottom of the bullets where all that greenish blue color and granules of power stuck to them. And it's also weird that the powder formed like a rock and is stuck in the case's.
How many times fired/reloaded ? Did he anneal ? Did he use any liquid cleaner that could have gotten on the inside of the cartridges ?
 
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