Jeff Siewert

I mean, just the ones that I've looked at here recently, I found as much as 10,000 or 12,000 difference in that head space.

So stress corrosion cracking is something that happens from time to time in brass cartridges.

And stress corrosion cracking is caused by basically three factors have to be present.

The first is the material has to be susceptible to it, and brass is susceptible, okay?

The second thing you have to have is a corrosive atmosphere.

And for brass, high nitrogen content is corrosive.

And then the last thing you have to have is a residual stress pattern in the material.

So typically what happens is the case looks just fine when you load it in.

But internally, what's happened is there's a crack that has gone partway into the case wall.

And then that crack moving into the case wall relieves some of the residual stress.

And the case no longer, I'm sorry, the split no longer runs.

It doesn't progress any more deeply into the cartridge wall.

And so everything is happiness until you've

you fire it.

And then what happens when you fire it is that, that split pops the rest of the way through the wall and you're left with kind of what you see there in the image.

Okay.

And,

And it happens with center fire.

It happens with rim fire.

The next slide shows 17 HMR with varying degrees of stress corrosion cracking.