Yep, I've dented a few myself.....fine to shoot and the brass will reform to the chamber........
Does it affect accuracy? It can, usually to a small degree that won't be noticed by the average shooter......if the dent caused the bullet to have run-out......causing a yaw as the bullet enters the barrel, the groups will open up some........it also changes the volume of the case........
Now, that said, this is not good if your trying to achieve bench rest accuracy.......and trying to get the last bit or accuracy out of the gun and load.......
I've found, that constancy is the key to producing accurate loads........an old friend, who loaded for the .243 super rockchucker, (6mm/06) would take his loader to the range with him.....He marked the case so it would lay in the chamber the same each time, and reloaded the same case every time....he measure the case after each shot and trimmed and reamed as necessary......he figured it took the case somewhat out of the equation.....he cleaned after every round, and allowed the rifle to cool between shots........he was anal about it.......that rifle, with his loads was about the most impressive long range machine I've ever seen.........it amazed me as he was able to hit crows at what I estimated was over 600 yards and did it most every time......this was before laser range finders and such......I don't know how he did it......but he did.........I could barely see them with the naked eye........
However, in most cases, you probably won't notice it..........
