Apologies if this is a silly question.
I shoot a .300wsm

I've been using Norma brass in the past and due to poor availability, I've gone to Winchester. I've never used it before. These cases have been fired 3 times. When inspecting them after a clean tonight, I noticed a dead straight line that runs the length of the case. On this one case the line will catch my finger nail. There are a few other cases that a line can be seen but my finger nail won't feel it.
From what I've read, I understood that brass shells were formed up from a brass button. These lines look like some kind of seam??
I've never seen anything like this with Norma, Lapua or Federal.
There's only one on each case, so it's not an impression from the chamber.
No line can be seen from inside the case.
What is this line?
Is this typical of Winchester brass?
Should I be concerned that my nail catches this particular line?
Thanks.....
