Just test-fired 3 new barrels on my new Mauser 98 go-to bolt rifles. 30-06 and 300 win mag, zero issues with fired brass. On the 375 Ruger, a super-thin shiny line on the upper case about 3/4 from the shoulder and a slight bulge at the base of the case. Fired primers look normal with no issues. For whatever reason, I can't upload pics here today to show it.

This is new factory Hornady 270 grain ammo, not handloads. Both fired cases look alike. I have seen slight bulging at the base on fired cases before on some hot handloads, but not factory loads. No clue what the shiny thin line at the upper part of the case is, but it is not inside the case and you can just barely feel it trying really hard with your fingernail.

The chamber looks like a chamber should look on a new custom barrel and nothing I can see that would cause that line.

Is this something I should worry about?

Also, to my amazement, the 300 win Mag with a 180 grain bullet clearly had more felt recoil than the 375. I fired twice, side by side, it is not my imagination.

The line has to be from a score in the chamber. The bulge is simply a sign of the tolerance between brass and chamber. All guesswork, of course. I have not seen it. GD

I've got a similar issue with a M70 FW 7 WSM I picked up at a gun show a couple years ago. The case shows a slight bulge in the chamber just below the shoulder.

I've only done a little load work with this gun and it shows good potential. It's a shame because the only way to fix it is a new barrel.

Probably the same cause. The reamer got a chip stuck on an edge and it scored the chamber. When this happens early on in the chambering job, it will clean up as the chamber is deepened; although this is less likely when the cartridge is one with minimal body taper and short. A flaw 1 inch in on a 30/06 chamber will clean up; the same flaw in a WSM chamber will not because there isn't enough taper. If the flaw is just shy of the shoulder, like this, it won't clean up period. GD

Greydog, does this affect the safety of shooting the rifle?

Absolutely not and, if you are experiencing no extraction issues, the flaw is only cosmetic. When resizing, it will be ironed out and will probably not even affect case life. I have seen this many, many, times. If it happened to me, on a customer's barrel, I replaced the barrel and saved the flawed one for my own use. Happily, it has only happened a couple times over the last forty five years. GD

Thank you Greydog, you just made my day.