So I'm hoping to know what the cause of this pucker/pinch in the shoulder. I was shooting at rock chucks Saturday and this case is the only one. I have heard it can happen if there's hydraulic pressure caused by too much oil left on the case after reloading. In fact have a friend that uses LW machine oil on his cases and doesn't really get them that clean after and this type of mark will show on some of his cases that I've seen. I've tried to tell him, but...

Anyway I try to be very careful about my reloading, and I've never seen this until now on my cases. FWIW it's a 22-250, win brass, 3rd reload, and I don't load them hot. Thanks in advance.

That looks more like a defect fold that formed when the brass was made than it does a lube dent.

OK...could it be less noticeable at first, but then more pronounced as you reload the brass? I will say that its not as deep or long as some of the dents I've seen that I believed to be caused by lube.

Also, reuse this brass or chuck it?

Thanks!

That was my first thought as well.

I have some brute-forced cases for Fireball made from 223 brass, and I had some of "that" happen. So, that's probably a result of original forming, or a possible lube dent you missed when loading.
Not a big deal as long as the bullet doesn't touch the dent when seated, in my experience, anyway.
The crinkly shoulders don't affect accuracy to any degree, as long as the neck formed on center -- I trimmed and turned all the necks on the brute forced brass, including any possible "donut." The cases shoot fine even if they are kind of ugly.
But the 22-250 has a bit of taper, and if you have to FL size them, that dent you have will move up into the shoulder/neck junction and might be an issue.
It won't move much, but it will move -- by then, I would guess that the body of the case is showing the stretch at the base.
So -- if you want, shoot and monitor. If not -- chuck it....it's just one case that doesn't meet your standards.

Did you clean soot off the area where it's dented, or was it squeaking clean as in the pic?

I've got a couple of boxes of .270 WSM factory loads and the shoulders on about half the cases look worse than the one in the original post.

I believe I did wipe it off with a dry rag, but that was about it. I don't get a lot of soot seeping to the shoulder with this rifle. I had a 7-08 that was another story.

The reason I ask is that I have seen brass, usually well sooted in the neck/shoulder area, which I suspect didn't seal well right away so there was high pressure gas both inside the case as well as a very small amount outside the case around the shoulder. Obviously, if that high pressure gas is trapped even momentarily after the bullet exits the muzzle, the pressure inside the case can drop more rapidly while the high pressure gas is still trapped very briefly outside. Even a tiny volume of high pressure gas can increase greatly in volume and could cause a crease or dent like you see there. I would expect that there would be some soot thereabout however.

Good point. Hadn't thought of that possible situation.

I have two cases that are factory new that look just like the one in the OP. One is a R-P 7 Mag and the other is a Winchester nickel .223.

I have a couple pieces of RP 270 Win brass that I have reformed to 256 Newton that have a very similar dent in the same location. I believe that my dents were caused by too much lube.

I'd throw it away if it were mine.

The defect is small enough I wouldn't toss it.

It the fold went all the way through the brass, that would be different.