Something new, what causes this?

[lcclower]

I have some once-fired 30-30 cases with flattened sections on the rims.
This is new to me and I wonder if anyone here has seen the same, and what causes this flattening?
Image at https://drive.google.com/file/d/1zzoCMKpKD_Pfch3AdQjyuNss_2kG40PR/view?usp=sharing

[Ford SD]

From you rifle ??
or range pickups ?

i could be wrong but i believe it is from a fixed ejector
(ejector is in the side of the receiver ...not a spring type ejector that is in the bolt)

Done when bolt moves back and brass hits the ejectore before leaving the rifle

[TurnipEaterDown]

It looks to me like the rim is bent, or at best has a compressed section.
I would confirm this through measurement across the rim bridging that section, and a measurement avoiding that section. It should measure as if it were thicker cutting across that section vs. not, if the rim is bent. If part of the rim is compressed in a section, you should be able to see a gap there against your measuring tool, where the tool should obviously be coincident with the rim surface otherwise.
It seems that the support structure for the case head in whatever chamber that they were fired in isn't a one piece bolt head, something was modified, or there was some misuse/pressure abuse.
Individual thoughts are what you make of them, and there is but one picture w/ no physical examination possible, but I think I would measure up some selection of those cases pretty carefully before deciding on using them. Rim dimensions (OD, thickness), case head dia for expansion, COL for stretch, primer pocket for expansion, etc.

[725]

Looks similar to over pressure to me.

[trails4u]

I have seen 30-06 GI brass like that......but have no idea as to cause.

[Hick]

I would check the surface of the bolt.

[Winger Ed.]

i could be wrong but i believe it is from a fixed ejector

That was my guess. Something like a Springfield 03-A3 type ejector.

[Michael J. Spangler]

Lack of lube teamed up with a steel hammer in a Lee Loader.
I know I’ve seen some Lee Loaders that look like someone used a jackhammer on them

[WRideout]

One possibility for a bright spot in one place on the rim is high pressure causing the brass to flow into the extractor cut on the bolt face (ask me how I know.)

Wayne

[BentSprings]

I'll second the Lee whack it loader in the hands of someone who needs some instruction.

[barrabruce]

I’ll third the Lee loader brass.

[uscra112]

My firewall won't let that Guuugle file load.

[Milsurp Junkie]

Maybe a dirty/rusty ejector/extractor on a single shot rifle. With an overly energetic closing of the action?