I've bought quite a bit of Hornady's Creedmoor brass, as well as their loaded Match ammunition, over the past three+ years. The brass is visibly and obviously different between the two in terms of where annealing coloration ends on the body. It was always easy to separated my fired brass on that basis. I have never taken close measurements to see whether any dimensions are different.
I also haven't bought any component brass for some months, which I say in case there's been a very recent change I'm unaware of.
The point stands, though, that in some instances the brass _is_ different, even if only in terms of final anneal flaming. ...or the component brass and ammo brass could be coming off of different lines...
