Cold bonding of plated ammo.Read this.

[Shadowrider]

I think it is like galvanic corrosion.
You have dissimilar metals together and they basically weld to each other. Street terms forgive me if I botched up the explanation.

That's exactly what it is. Where you went off the rails, so to speak, is with the dissimilar metals. The cartridge case is brass, the plating or bullet jacket is copper. Well brass is comprised of 70% copper so it's not very different at all. The other component of brass is zinc and that's interesting. I'm wondering if wet stainless pin tumbling could be the precursor to the process. Because I know for a fact that some of the chemicals added for cleaning (dawn and lemishine) and chemicals in tap water (chlorine, fluoride, minerals) will dezinc brass especially when combined with heat (drying in an oven ain't good, not good at all).

I've shot jacketed rounds that are far older than 10 to 12 years and had no issue. I think it's going to take some really special planet lining up type conditions to get galvanic corrosion going in modern cartridges without some help to get it going.

 

[dennishoddy]

Here's another potentially interesting thread with some history on the subject:

Bullets Bonding to Case (The Firing Line Forums)

Your link showed the same thing I've experienced with milsurp ammo. Must be one heck of a bond to make a kaboom.

 

[lee1000]

I'm not worried about it and I don't think it has anything to do with plated bullets exclusively. Billions of copper jacketed/plated bullets are shot every year without issue.

 

[magna19]

A lot of KaBooms have been blame on these mysterious phenomenon. Id bet they are reloading errors by the reloader.

 

[Sanford]

Your link showed the same thing I've experienced with milsurp ammo. Must be one heck of a bond to make a kaboom.

That's what I was thinking too. Seems there would have to be something that encourages the chemical/galvanic process going on - perhaps frequent wide swings in temperature causing the less dense of the two similar materials to 'condense' into/on the other? Would be an interesting project for lab research, but if it was at all common I'd think we would have heard much more about it in reloading circles over the years.

 

[grwd]

A lot of KaBooms have been blame on these mysterious phenomenon. Id bet they are reloading errors by the reloader.

nice handy excuse.