FWIW,
Dents are usually caused by the case striking something on the way out or hitting the outside of the gun. Look for brass marks on the edge of the port or the side of the slide. When a case is ejected, it is struck by the ejector, and pivots around the extractor. At times, the case will actually exit the port, roll around the back of the port, and strike the slide behind the port.
In some guns, the ejection is slow and the fast moving slide strikes the case before it fully clears. These things can usually be corrected by a little tuning of the ejector and extractor, but there is no way I can describe what needs to be done; it is often a matter of trial and error.
Reloading should not be affected if the dents are minor.
Jim