Today I ran across some loads that I did for my Model 29 back in 1974. They were meant for a hog hunting trip that I was going to take (to Texas, IIRC). At the last minute the trip fell through and the loads got put away for another time. They were stored in a sealed container with dissectant in my parents basement where all my reloading stuff was then located. We moved back into the house where my parents lived a couple of years ago.
At any rate, the loads were 22gr of 2400 under a 240gr JSWC. This was a load that I had worked up in my 29. It was stout, near the then recommended maximum, but performed well and didn't show any pressure signs in the gun. On the notes on the box, I had put them up with brand new WW brass. That jives with my memory as I usually put up loads meant for special hunting trips in new brass.
Looking at them today, they still looked pretty good, a little pantena on the outside of the brass, but all-in-all, looking pretty good. However, since they were approaching 40 years old and the load was over what is NOW the recommended max load, I decide that instead of following my first inclination to just shoot them, I decided to pull them apart with an inertia puller, salvage the bullets, brass and primers and restuff them with a less frenetic load.
I started pulling them down, got about 10 rounds into it and noticed a number of them broke down really easily. I looked at the brass on those and they all had cracks either at the mouth or in the middle of the brass approximately where the base of the bullet was. I then checked all 10. Those that pulled easily were all cracked and the tough to pull ones LOOKED ok. I then check all of the remaining loaded rounds and they all looked ok. Absolutely no visible cracking anywhere. I pulled all the rounds (there were 100 total) and 55 exhibited cracks in the case after pulling. I also checked the insides of the cases and they were, indeed, bright and shiny indicating then new brass (back then, I hand washed brass and even once fired were dark on the inside).
The only thing I can come up with is that the brass somehow age hardened enough to crack the cases when the bullets were pulled. I've not heard of that, before, as in the past, I have shot countless rounds that were pretty old without any undue problems. The only reason that I didn't shoot these is because I was a little concerned because it was a pretty heavy load that, although was in-bounds back then, would be considered overpressure now.
I am also concerned about the 45 cases that APPEAR to be ok. Can I trust these? I don't intend to load them heavy as I am punching more paper than animals these days, but I still have it in the back of my mind there might be a problem with these supposedly still good brass.