Hi. I reload 29 calibers and have been doing so for over 40 years. I work on a rifle/load until it will shoot < .5". I have purchased 4 Axis rifles last year (and will buy another tomorrow!!).
I only mention this because, as mentioned above, these dents look WAY too consistent to be anything other than debris in the chamber. I'd take it to a gunsmith with a borescope, if nothing other than to eliminate this aspect.
One of the cases almost looks like a 'gas trail' from the case mouth to the 'dent'... strange indeed, but interesting!!!

ron