I think the OP is talking about the chatter marks around the rim.FC/LC/AE 5.56mm from Federal sometimes looks like that. The 223 is more polished and the 556 is usually neck annealed but I got a bag from FC the other day with no annealing and kinda looks like that.
Those are there to give it more spin as it comes out of the EJECTION PORT.
You can't just assume which end I'm talking about. I reload case fluid.Fixed it for you.
My mistake, I thought we were talking about Pew Pew dust.You can't just assume which end I'm talking about. I reload case fluid.