Case neck splitting and other oddities

[MrK.]

I have been taking a couple guns to the range every week to verify zero prior to the upcoming deer season. This wknd it was my Marlin 30-30 and my 14 inch T/C contender in 7 TCU. The Marlin was fine, it shot like a 30-30. The TCU was spot on grouping at 1.3 inches 1/2 inch off target which I attributed to the crosswind. I shot only 3 shots because I only had 11 left from a batch of 100 I loaded back in 2007 and wanted to make sure I had enough to pop a doe or two. When finished I examined my cases and noticed that all three TCU cases had split necks. One had a circular crack around the neck-shoulder junction so severe that I was able to pop the neck off with my thumb. When i got home I examined all of the previously shot cases and none had split necks. This is the second firing of these cases, they had not been annealed. I last shot this gun about two years ago. I decided today to pull the remaining 8 bullets, deprime, anneal, neck size, and reload. When pulling bullets, 3 of the 8 broke at the neck-shoulder junction with the neck staying on the bullet.

Winchester .204 Ruger cases, Win SR primer, Speer 145 grain SP, 26.5 grain H335

I have read threads on here and other places about brass hardening as it ages but I am not sure what to think. No split necks two years ago.

Thoughts?

 

[CaptainMal]

The bullet jackets reacted with the brass and stuck over the past 13 years. That's not very long yet yours are in some way "welded" together.

Might be related to something on the bullet or in the case neck that created such a problem so fast. Often ammo decades old would do that but 13 years is not all that old.

Trash the brass and get new stuff.

 

[243winxb]

Chemicals during cleaning or over working the brass. Or both. Annealing may help if over working the brass.

I formed using 223 brass. No annealing. Many 7 TCU split necks.

When reloading 223 brass, use a bushiing die or neck turn.
Federal 223 cartridges from 1997
Factory ammo fired when new. Reloaded and stored since 1997. Nothing new, happened before with brass washed in a vinegar solution. But this brass was not washed, just wiped and loaded.The cause seems to be over working of the case neck when FL sizing. Loaded in 1997 IMR4198-20.5grs Win 55 gr fmjb.

On some brands of brass, the expander is all most impossible to pull thru the lubed necks. Factory new brass may have a "donut" at the neck/shoulder junctions.
https://www.ampannealing.com/articles/42/annealing-under-the-microscope/