Glad to hear you got the first rifle replaced without fuss. Good on them for treating you right.
The second set of photos you post, looks more like a (deep) scratch to me. Perhaps a consistent scrape from when you load the magazine, or feed the round out of the magazine?
Next time you're at the range, try loading a cartridge directly into the chamber by hand. After you've fired it, slowly and carefully extract it (don't let it fling out of the action).
If it shows this mark, then the mark is due to something in your chamber. If it does not show this mark, then the mark is being made before it is getting into your chamber. If it bugs you, you could look to see what is causing it, but FWIW it's just a cosmetic problem, it is not going to be unsafe, or hurt your accuracy, or hurt your brass life.