I'm hesitant to post about this, because I know I'll catch heck for it, but here goes anyhow.
I started a thread a while back about a bunch of .223 ammo I loaded a year or so ago, that was all cracking in the neck area when fired. I was trying to figure out why. The only real difference in my loading recently was that I started wet tumbling a couple years ago, and some surplus powder in those particular loads. I looked at the dies, and a replaced expander, wondered if that could be a factor, I don't know. Now I have some .270 brass from a year or two ago, that about half of it cracked in the necks when fired. Different powder of course, but also wet tumbled.
I know a half dozen guys will now tell me that it's the brass, brass wears out, and I just need to anneal. That or there's some ammonia or something hiding around my loading area somewhere (not). That's fine, except for the fact that this is something new. I've had cracked necks before, typically in 20 year old reloads, not in recent reloads. In looking around online, I've seen at least a couple others complaining about increased brass cracks after wet tumbling.
I can't say for sure, and it seems like most everyone says it can't hurt the brass. That may be true, I don't know. All I know is that I have brass cracking like it never used to, over decades of loading. Maybe it's something else. All I know is that I'm going to go through any rifle brass that I've wet tumbled but not loaded, and anneal it all. I also used to tend to tumble longer than needed, and used more Lemishine than necessary. Any brass I tumble in the future will get a much shorter ride in the tumbler, maybe an hour instead of three or four.
I'm really not looking forward to finding more wrecked brass as I go through more ammo that I've loaded in the last couple years.