I've seen rifle ammo (.30 carbine Aguila) split on the first or second firing, but I was just sorting some 9mm brass after tumbling, and found my first split 9mm that I can remember. I'll post a pic later...but it's a Win case, split from the mouth about half the length of the case. I think it's one of my reloads (reloaded an unknown number of times...but I'd be surprised if it was more than half a dozen). I pick up range brass, so it could be someone else's...but the primer is silver in color (like the CCI primers I use) and I think factory Win brass uses brass colored primers. I thought pistol brass was supposed to get lost before it failed...esp when loading on the low end.