Dents in your brass indicate crap in the chamber, whether it is lead,copper,brass or even thread off a cleaning patch. A raised ridge in the brass with corresponding "stickyness" on extraction would indicate a problem in the chamber, i.e crater or gouge. As for chambering "belled"cases, you are basically using the taper in the chamber to "crimp" the brass. Brass is a
lot softer than barrel steel. If the chamber is well defined there are quite sharp edges especially at the back of the chamber, could be where the shavings are coming from.
The sharper dents are from contacting a sharp edge, could be from rough chambering or extraction of rounds. Slow down, unless you are in a speed event and you don't care about your brass, ( or the zombie apocalypse has started and your life is in danger ) a little care will result in extended brass life.
It never ceases to amaze me when I see blokes cycling ammo as if their life depended on it, and before all of the "
have to have a quick follow-up shot" comments start, trust me I have done a f@cking lot of hunting and been able to mow down mobs of pigs/goats,etc on plenty of occasions without having to cycle the action like Wyatt Earp.