Most likely shot out of an AR platform...you will notice these dings on .223/5.56 rounds as well. The brass hit the deflector after being ejected. As long as they are dings and not huge dents that deform the brass or deep cuts that would ultimately weaken the brass...it will be fine. If you shot the brass in a bolt gun, it would likely fireform the dent back out.
I pick and choose my brass when I pick it up off the range floor and it hasn't be through my own firearms. I also always Full-Length size all brass that I pick up.
Ditto that. There's hardly enough deformation to matter. I'd load 'em and shoot 'em no question.
I scavenge range brass from time to time... actually a LOT, even digging stuff out of the dirt. Now that I have a stainless steel media tumbler, it doesn't matter how aged the brass gets, the STM gets it cleaned and I do recycle some that is really beaten up.
yes, they are from the brass deflector on the AR platform. I had the same problem with my LMT until I put Velcro on the deflector = no more dinged brass. Will be fine to reload as long as the ding is nut cutting into the brass.
you can see the Velcro on my deflector in the pic here, A MUST FOR ANY AR RELOADER!!