Stuck Case in Chamber

[Marky_mark]

@Marky_mark do you think carbon ring would have anything to do with it? I wouldn't think so since it's only a here and there

It might explain the velocity increases
Use a bore scope and check
if you don't have one you could just scrub it with jb bore paste to get it back down to metal
But i think the stuck case issue is what Alex wheeler was talking about in those videos.
My Buddy has the same issue with his 7prc
I have a wheeler reamer kit that I rented from this site arriving any day.
If you take a bunch of measurements. Compare new brass to stuck brass to the reamer specs
It should answer a lot of your questions

 

[Marky_mark]

If your brass is larger that what your chamber is
That's 100% the reason why it's having hard extractions