This thread generated a lot of attention. Very satisfying, and the comments and suggestions are most encouraging. This case was media cleaned, as were all of my early cleanings. I do all wet w/sis pins, now. This was in an indoor range that is policed real time by the range officer. Brass doesn’t sit more than 5 minutes, if that. I grab my rounds as I shoot them to ensure they don’t get pushed down range by the RO.
When testing loads, I restore all fired brass to the same Berry’s ammo box that I put my new loads in. As I was decapping my brass I found this one. So I’m 99.5% sure it’s my brass. The other 0.5% leaving open the chance that it flew over from 3 booths to my right, landing in my ammo box as I bent to pick up more fired cases. I do grab range brass when I can, but I throw that into a pocket in my range bag...no mixing of my loads, my factory rounds, and pickup brass if I can help it.
The brass was not this color when I reloaded it or when I placed it in a magazine. It is flame broiled. It is possible that this case had internal corrosion that I didn’t detect. My brass was poorly stored for over 20 years before I began reloading. Some of the cases were pretty rough with verdigris as some of it got wet. Nearly all of my brass cleaned up pretty well with media tumbling, but I was unhappy with the amount of time and effort needed to clear media from the Primer holes.
I’m just glad that others have had similar case failures, and that failure in this section of the case should not produce injury to myself or my firearm. It has my attention, and I’m going to start tossing any case that gives me any concern. Brass is too cheap to willingly subject myself or my firearms to events as this.
Thanks again for the support.
instead of firing the 800 rounds I started pulling pullets: after that I posted the results. All of the experts claimed the problem could not be caused by my finding. I have more ammo from the same source but refuse to fore the ammo in the trashiest if chambers.